I'll approach the question by taking the listed parameters and offering some thoughts as to time/cost/ money. Overall, building up a working bicycle from a bare--or nearly so--frame is extremely satisfying experience interspersed with periods of frustration, disappointment and sometimes boredom when a project drags on too long (& who's to say what that is, though a significant other can certainly be counted on to offer a concrete opinion of that).
I see several aspects of this proposed project where parts can be sourced relatively cheap due to the desired parameters of the parts being ones that are in somewhat lesser demand yet with decent inventory in most places.
Aspects of the project that offer opportunities for cost savings:
--Steel frames are generally less expensive than non ferrous alloy or carbon. Spacing can be changed via cold setting to accommodate various hub widths leading to a wider variety of wheel selection as well as gearing options. Durability of a corrosion free steelie is excellent.
--Used rims for use with rim brakes can be sourced most places easily. Frequently, rim brake wheels, whether 26", 700c, or 29ers, are discounted due to lower demand. They also are common in the bike coop setting for the same reason. Private party sales as seen on Facebook, eBay and the like, I've chanced to come across are notable for some wheels being sold for just a few dollars. The 26", rim brake, freewheel compatible hub (rear) is arguably the most heavily discounted type of rim on the market today. Even if the least expensive option doesn't interest you, quality carbon and aluminum wheels that sport the low-demand specs of rim brake or even just having a 10 speed freehub (for a road rim) but are otherwise very high quality are sold at a heavily discounted price. This can present a nice opportunity to "upgrade" your ride with a high quality wheel set but not spend the kind of money such a wheel set commanded when it's specs were the new thing.
--The trend toward single chainring cranksets with 11 or 12 speed rear cassettes is another aspect of today's market that favors your project and it's call for something like a 3x8 drivetrain. Although it seems to me, new triple cranksets haven't experienced a decline in their price points related to the aforementioned change in many of today's bicycle builds, that does not hold true for the used market, where triple cranksets with relatively low use are available for a fraction of the new cost. The price trend of new front derailleur's, on the other hand, has seen a precipitous decline. Especially on the mountain bike area of the market. I've acquired new Shimano XT, SLX, and SRAM XO front derailleurs within the last 18 months that were all less than $10 USD. My hardtail is currently spec'd with an XTR front der (a now generation old, FD-M9020) that was included in a sale of 10 speed XTR shifters. While all the items were used, the price I paid was 33% of the cost of new. Again, your choice of a 3x8 drivetrain, opens up many avenues to choose from ranging from used, very cheap components to selecting high end components that are heavily discounted. It's my impression that the NOS (New Old Stock) market for high end components (Shimano XT, XTR, Campagnolo anything) continues to see price points fairly elevated and not a good value. Due to Shimano's propensity to trickle down technology, paying a full, expensive price for yesterday's XT or Ultegra component doesn't make a lot of sense when, for far less money, with perhaps a bit of weight penalty, one can buy today's Alivo or 105 or Tiagra component and enjoy equal or better performance while paying less.
The time it takes to shop for, acquire and connect all these parts to your build is not insignificant. I spend several hours a week in my garage shop working on mine and others' bikes. It's a labor of love and as someone mentioned, it's far better than watching TV. I also enjoy the stories of folks who visited the bike shop, coming away with two trued rims, a now-quiet disc brake, absent the funny vibration and steering feel the bike came in with by virtue of an adjusted headset. The punchline being the 3-figure bill and 2 week hiatus from cycling endured by them while I spent some quiet time in my garage on a Saturday morning doing the same thing to my ride, which I took out that afternoon, leaving my money in the bank. It's good to have this hobby. So enjoy your build.