I've have my 1985 240DL serviced by Larry in Long Valley for the past 14 years. He only deals with Volvo's and was factory trained. I've never had an issue with him.

I had a wiring harness fail on me. I took it to Bridgewater Volvo (the closest too me). They wanted $100 to even look at the car, not even fix it. I grudgingly did it because my dash lit up like a Christmas tree (Lambda, parking brake, brake failure, alternator, light out, maybe more), and I didn't want to chance losing the car. They called back and said they wanted several hundred dollars for the wiring harness job, well the car isn't even worth that much. I took it Larry's he had me up and running for under 50.

Try Steve Kafasis in Cranbury, NJ.
If you can leave it for a week or two and if you offered to help with the "grunt" end he might be interested in doing it(he did a swap for me from my totalled 90 240 into a 90 240 with a blown engine that I gave to my nephers/niece as a starter car).
Nice thing is if you do offer to help you can do a ton of work on the engine bay during the swap (sour/clean all surfaces, do some paint work, recover and the harness with fireproof sleeving and reroute, etc, etc).

but I don't think you will get a quality job for under $750. Remember it does involve a fair bit of disassembly and bodyremoval (hood and front crossmember make it a lot easier). Plus you don;t know what else can happen (busted manifold studs, etc) plus include all new motor mounts, gaskets, belts).

I am not in NJ but I am in the business of servicing Volvos. We always charged 20 hours labor for an engine swap at the dealer. I think that is a little bit of a gouge, but not too bad. Something in line with about 15 hours would be about right. In my shop that would be about $1050.00 plus fluids and misc. parts. They want $950.00 out the door to install your used engine, that is not out of line at all. Remember, Cheap, fast, and good, you can have any two that you want. From your post you are looking for cheap and good, well aside from being a rarity if it is truly cheap AND good it will not be fast. Price it around a little more and see if you can't find someone that is in the middle of the road, not the cheapest and not the most expensive either. I find it is better in the long run to spend a little more money up front and get a better job done. The trick is making sure that you are in fact getting what you paid for and not just pi$$ing away more money.

Good luck,Mark