We all like a bargain. Rich people don't get rich by paying top-dollar for everything and poor people sometimes have their purchasing decisions limited to what is in the bargain-bin. Whether rich or poor a lot of time can be spent hunting out bargains, however, all bargains are just another ploy to get some money from someone's pocket. Hence, rather than just scout for bargains it can pay to know a little bit about how a given product - in this case cycle clothing - gets to be marked down.
This answer takes that perspective into account.
Starting with what you see on the shelves, in the bargain bin or online, a lot depends on how tall or short you are. That is a huge factor in affordable bike-gear and here is why.
Most LBS suppliers bring in a certain amount with the start of each season in a mix of sizes - lots of medium and large and not so much x-small, small and x-large. Shops then purchase from the distributor so as to stock all of the sizes with the popular sizes in quantity.
Inevitably, as the season goes on, the popular sizes sell out leaving the less popular sizes, i.e. x-small and x-large. Then they go back to the distributor to re-stock. Somehow the distributor are always able to source the x-small and x-large sizes, however, they sell out of the popular sizes before the season's end (or not if that year's designs are not well received).
Hence, a popular item in a popular size will become very hard to find at some point. When this happens the shops with the x-small and x-large sizes left will have an unsellable product, taking up valuable shop-floor space. They then need to discount the product to get rid of it as soon as possible. Because the markup on clothing is high (and has to be because of the situation described), the shop can discount heavily the end-of-line items without making a loss.
Therefore, if you want discount cycle clothing it is best to be really tall or really short.
Another source of clothing that you might be interested in are places such as TKMaxx. Where do these places get their stock?
When a distributor brings in a new range of clothing they get a complete set of pre-production samples in all the sizes and colour variations. These samples are as good as the finished, production articles but not for retail - they are to show the retailers so that they can place their orders. The samples cannot be sold in competition with the retailers as that would upset the retailers. Instead these items have to be sold through a different channel. TKMaxx are the specialists in being able to sell such collections of one-off samples. They buy entire sample sets and sell them as seen at considerable discount. Therefore, you will want to keep your eyes peeled for whomever your favourite cycling clothing is distributed by and work out whom they offload the sample collection to.
The major online specialist cycle retailers - 'Wiggle' and 'Chain Reaction Cycles' in the UK only have so much latitude in how far they can go on prices. They do get specialist rates from the distributors but if they go below an acceptable price then the distributor can threaten not to supply them. In practice this works.
The big online retailers have costs and problems of their own. They only compete on one thing - price. Postage is at a preferential rate to them but it still costs, particularly when you buy all three sizes and return the two that do not fit.
Their own-brand directly-sourced without distributor clothing range is also a bit naff - akin to 'Woolworths Winfield' rather than 'Adidas' genuine originals. This may not matter to you, but people do sneer, myself included. Nothing marks you out as a cheapskate in the cycling world more than own-brand clobber from offshore, online-only retailers.
Also in the retail channel are grey imports. This is where a specialist cycle shop - maybe only dealing in high-end road bikes and apparel - goes to somewhere else in the world to get their goodies, bypassing the distributor.
This presents an interesting situation when things go wrong as the grey importer does not have the security of having a distributor to return faulty goods to. The distributor will see returned items as 'fakes' and not have anything to do with them.
In the UK there is 'Lidl' - a German supermarket that does cycle clothing from time to time. Funnily enough I am wearing some of their £10 SPD shoes right now. You have to wait for them to get a batch of cycle gear in and then it is not really quite as good as the real stuff. Many synthetic fibres are really bad for holding the bacteria that give you body odour, and I suspect that the Lidl clothing is of this ilk.
Given the many ways that the whole thing works, I highly recommend buying from your local bike shop if they have taken the time and effort to put a range of clothing together for their customers to try and buy. This is not the chain where head office have to approve every penny, this is the proper local bike shop where the owner manager is out the back or helping a customer, Allen keys in hand.
If you are wanting a deal and don't mind colours and a bit of shop soiling do ask them what have they got out the back that is in your size and that they are desperate to get rid of. They are bound to have something and, so long as they are not going to lose money on the sale, i.e. trade-price + taxman, you can probably 'take it off their hands'. This will still help the shop with their weekly cashflow, you will get to test the fit before you buy and everyone should be happy.