$ 8000 seems like an awful lot for a B20 rebuild unless you are having a lot of custom work done to the head, dual springs, hot cam, porting ….. It has been 6 years; but I rebuilt my B20E and with machine work and parts it came to less than $2000 Cdn at the time. I did the tear down and re assembly of the engine. Machine work consisted of reboring the block for 0.030 oversize pistons, fitting hardened seats on the exhaust valves, 3 angle valve job, insert new bronze valve guides, resurface rockers, press in new camshaft bearings and a balance of the rotating assembly. The crank was good which saved money because all I needed was to replace the shells on the mains and con rod,the original timing gears were still in good shape and the original oil pump was fine (although I added one of those reinforcing rings and a high pressure spring. Parts consisted of all new bearings, new cam, lifters, push rods some new valves (severe rusting), gaskets , water pump, hoses and upgraded timing and rear covers with neoprene seals. If the crank had required work and I had elected to install steel timing gears that probably would have bumped the price by $500 - $700 depending on how much work the crank required.
The one thing I did not do was deck the block which is a mistake if you are running a high compression engine. If a machine shop does everything that can add a fair amount of $ because they have to do the assembly, measure and then disassemble to machine. If you feel competent you can assemble and measure and disassemble and then instruct the machine shop as to how much you want removed. This saves a couple of hours of cost at the machine shop.
At the time IPD offered a kit of pistons, bearings, gaskets and some other stuff which provided for a significant saving over individual purchase. That option does not appear to be around anymore; but, send them an email and see if they might do something for a complete package of parts for a rebuild. You could try the same thing with VP Autoparts and Iroll. If that does not work out, Rock Auto lists a lot of the common B20 parts for very good prices. I know what Mahle pistons sold for when I did my rebuild and I see what they sell for today. If that inflation applied to all the parts then I could see this heading to $2500 if you do the R&R yourself. I would think that if you drop your removed engine off at a shop that you should still be able to get it back for less than $4000.