Around 35 basses. I don't actively look for more but they seem to pop up anyway (more like I'll check bassgear.com or the classifieds here just for grins) and if it's a better than average deal and I'm in a position to do something about it, I might. I have no problem talking myself out of impulse buys. I'm too entrenched in running "what-ifs?" to make bad decisions very often. The last time I did that I missed this bass for $3500: a year old Fodera Emperor Elite 5. Duh. Can't win 'em all.
I basically have three reasons to buy: cool enough to crack the current lineup (this one gets harder and harder all the time), resale value (usually immediate) or old and cheap (I didn't really need the old Kramer DMZ4000 or Electra MPC Outlaw that I found for next to nothing at a pawnshop)

. Sometimes it's a combination of the categories. The Ambush bass I picked up is a great example of that, it basically fell in my lap, it's a great bass and the price was excellent. Or my MTD635 that GC offered to me for a little more than 1/2 of what they had it tagged for. No regrets on either of those purchases and they both get gigged so they help to pay for themselves.
I think largely because I have a reputation of not BSing around when it comes to making decisions, I get lots of people contacting me about potential sales.
As far as maintainence, I do my own and I'm lucky in that my hands don't sweat so strings typically last a long time.