Having worked in the auto air industry, and seeing the mess people often end up creating trying to fix stuff to do with auto air on the cheap, my advice would be to save up and get a reputable A/c shop do the whole job (with warranty) I have seen people use old/incorrect O rings, forget to tighten fittings (overtighten/ crack alloy tubes/snap fittings off) then just bring it in for "a regass" and wonder why the next day it isnt working? If you get the shop to do it, they will add oil, use the right o rings, put dye in it to see if it does leak in future. I know for a fact that when we had someone come in and ask 'just for a regas' we just did the regas... didnt even look at anything else..... If they asked for a service, they got the system inspected, o rings replaced, receiver/dryer replaced, oil and dye.....
I am not saying you dont know how to do it, or that you are incompetent or anything, I just know that alot of the time when it comes to air conditioning, which is a bit of a 'black art', even I myself would rather save up and get a shop to do it, so if there is any problems, I can take it back. It is very easy to pay $120 for a regas, find it leaks, fix what you think it is, take it back for another $120 re- regas, find the tx valve or oriface tube is no good, fix that then go get another $120 re-gas...... find it is still not working for some reason
and have to take it to a shop after spending all that money, only to get a specialist to re-do it all and cost you another $500 on topThis is just my opinion, I have seen it many times..... just find a reputable shop, talk to the owner, tell him what you have done so far and see if he can do a decent price for you.