My two cents
Let me preface things by saying that collecting original artwork is unlike anything else I've ever collected in my life. It has a sense of history and meaning to it, and depending on the piece you acquire, you can sometimes actually feel a surreal connection to the writer/artist team associated with the page. If you're not careful, that feeling can become quite intoxicating.
Romanticisms aside, original art is largely a one-of-a-kind business which means it has the stench of exclusivity to it. I have a love/hate relationship with that. The hobby can sometimes feel like a who-do-you-know and how-much-cash-do-you-have hobby especially when it sometimes feels like you never had a shot and some really cool artwork whereas some people seem to have repetitive opportunities to do so. Rather than get frustrated or conspiratorial, what that often means is that you need to be plugged into the community more. I think it's worth the time to do so if you're looking to join. It isn't a huge community so you can get to know the regs rather quickly.
When it comes to buying artwork, my suggestion would be to have rules to the way you buy/collect and to only buy/collect within your financial means as you can easily be drawn to buying big ticket items once you tread down that narrow path.
This is what generally works for me:
1) If it is not going to be displayed (framed), I'm not buying it. My tastes are too pricey for me to collect like baseball cards.
2) I generally only buy paintings so unless a really cool pencil/ink piece comes along, I typically pass on it. I recently acquired an Arthur Adams X-Men cover which justified breaking this particular rule.
3) I should be able to resell what I bought for what I originally paid.
4) Watch the market. Don't get drawn into buying agent prices who are out to lunch. Case in point: Alex Ross. His agent lists some of his work at 25k. You'd be lucky to get half that in a resale. Buy smart.
5) Limit one piece per character. Unless it's a costume variant, or something else that distinguishes it from the piece you already have, don't let your cash burn a hole in your pocket. If I feel the newer piece is better than the one I already have, I will sell the older one.
6) Try not to get drawn into the hype of an artist if you do not like their work. There's this one artist whose artwork I feel looks like it was dipped in water, yet others love his style.
7) Share pics of your artwork on comic art fans pages. It's a great way to meet others who share your love for the hobby as well.
8) If there is a piece of artwork you want, feel free to approach the owner and inquire in a very polite way. You would be amazed at how many pieces can be had especially if the owner finds himself in a sudden need for cash to buy something else he wants.
9) If you're unsure about a purchase, ask for a second opinion. Most people should offer you better advice than simply saying "if you like it, buy it".
I'm sure I have other rules I follow but those are the main ones. Hope it helps!
