Buying records online is something to do as a last resort for something rare you can't find locally. For heaven's sake don't buy from Amazon. Amazon is the biggest force working against the great local record stores that are still surviving. If there isn't a record store in your town, there probably was a couple years ago. Save the one the next town over and SHOP THERE!
Start by going to thrift stores, some have no records, some have few, and some have a lot. You will figure it out pretty quick. Generally priced around $1 each. You'll be sifting through some lowest common denominator stuff, but every single record you have mentioned in your other thread is in the bins at a thrift store somewhere. Garage, and especially estate sales are hit-or-miss, but you can really clean up if you find a good one. Most record stores also have dollar bins with similar fare to the thrift stores. Antique marts, on the other hand, are usually way overpriced and should be avoided.
180g is a scam. Tossing a few extra vinyl pellets into the press won't fix any earlier problems with mixing/mastering/cutting, et cetera. Plus depending on how sensitive the cartridge is to SRA, the extra thickness might make it sound worse.
