240d AC question

[Jaclson]

Hey guys. I bought my 240d over a year ago with a rebuilt ac compressor and a system that was leaky. After driving all over town getting opinions I settled on an independent shop that quoted $300 for changing the compressor to drier hose and recharging with r12. This included new o-rings and a new drier. Everyone else in Charlotte wanted $800 to start with. The bill came in at around $700 and I know that the drier was not changed by looking at it. That was 5/01 and the system is down again according the the fog in the drier glass though it is still cooling. I have 3 cans of r12 from moons ago and the leak appears to be around the return hose the goes from the expansion valve back toward the compressor. I am nowhere near the mechanic that some of you guys are but I have added r12 to systems before and observed a system being evacuated. Question is; should I try to rent a vacuum, try to find this hose (unable to find that name of hose in Fast Lane) and give a go at this or write a blank check to another mechanic and hope that they do me right?

As a side point, I was looking through old AC threads and noticed that newer 300's can have an under dash exchange leak problem that can cost upwards of $2500 to fix. I broke out in a warm sweat as newer 300d WAS my next dream car.