Listen critically to recordings on the archive. Make note of small differences in mics, capsules used, preamp used (if any) and so on. Key in on the best sounding recordings with the specific gear you're considering, as those are examples of the possibilities that a certain rig will provide in terms of sound quality. (Generally outdoor gigs sound better than indoor bc there's no room reverb.) Archive is your friend and you'll find your critical listening skills to improve the longer you are a taper. Importantly, ALWAYS trust your own ears more than the opinions of people on ts.com...ALWAYS. I learned this lesson the hard way and it cost me hundreds following the advice of people that hear differently than I do. Remember that people almost always have a bias to the gear they own....which causes their opinion to be skewed.
While I agree with others that you dont NEED top level gear to make good recordings, IMHO you do need top gear to make great recordings (when all other variables of live recording are optimized). Also realize that the base price of entry for a set of great gear is not necessarily linearly proportional to the price paid for good gear. Generally, to get top level sound, there's a premium to be paid to get top gear. Stated another way, it might cost 100pct more to get a 20pct sound improvement, if sound were quantifiable. That said, this generalization has changed a little bit of late as the market for used top end gear has dropped.
Ps: I'm a rare taper that loves blues but can't listen to TTB. Just don't like them at all. Susan...ugh!