I have no derailleur and cheap grip shifters on my schwinn pathway want to get new ones
The summary answer is that we can't know the answer to this question.
To give you an estimate we would have to know:
1. How long the work would take.
2. The per hour charge at the shop.
3. The cost of the parts needed for the repair.
Item 1: Based on your description it is difficult to determine exactly how long the repair would take.
Item 2: Different shops charge different amounts per hour.
Item 3: We can't know how much a shop will charge for parts or which parts you will need.
The best thing to do would be to get a estimate from the shop.
Any reputable shop will give you an free, no commitment estimate and promise to be within 10% of the estimated price when the repair is complete.
A Schwinn Pathway is a BSO, made down to the price point of $174 USD and looks like this:
From Amazon Link
Now a BSO is still a bike and still beats walking, but there's little point spending a lot of money on this one.
The specs show a bike with 18 gears total. I can see a triple front chainring, suggesting this bike has a 6 speed freewheel on the back.
The rear derailleur is labelled Shimano and will be a Tourney level part at best.
Depending on what else your bike is missing, it will need a derailleur cable (inner and outer) and a 6 position shifter. There's a good chance the grip-shift is broken assuming its still on the bike.
A photo of YOUR bike will be a lot more helpful to figure out what's missing. Please include a good clear photo into your question. I'm anticipating that other parts will be missing too.
For parts I'd suggest checking for a local bike cooperative or similar. New parts may be priced too expensive.
As for the grips - they appear to be that horrible gummy rubber that decomposes on exposure to sweat, oil, and air. It turns tacky after months and ends up as goo. You have three options.
- Replace the grips - cut the old ones off and shove some new ones on.
- Cut the old ones off and ride on bare metal. Workable depending on temperatures outdoors
- Leave the grips as is, but cover them in wraps of tape. Paper tape works reasonably well for a few months, till the goo of the old grips soak through. Plastic tapes tend to slide off. I've used heatshrink tube successfully for this but its not a common thing to have around in ~35mm size.
- combine 2 and 3, remove the old grips and attach some tape for comfort.