You can trade for them on the trading post or random events.
You can find paintbrushes by either looking it up in the Marketplace, OR when your lucky, you will get a paintbrush by random events.
A brown paint brush in Neopets is worth about 600,000 neopoints
You can get a free paint brush on neopets by either going to the giving tree or by trading with someone.
Not at the moment... You can only get mutant from the lab ray.
You can always search the auctions or trades to see if any are being offered.Alternately, you can get it at the Hidden Tower in Faerieland for 600,000 NP.
You buy one from a shop. Usually 40-50,000 neopoints.
The starter can't be traded (sold, traded, auctioned, donated). so you have to either use it in the rainbow fountain ( located in Neopets Central)or discard it. The normal one can be traded or used or discarded.
Buy the baby paintbrush and then go to the rainbow pool and paint the desired pet.
You should try the trading post. There are loads on there and although they are quite expensive, they are very worth it!
the lab ray- it's the same as jelly pets.
with a paintbrush, morphing potion, or secret laboratory map...or Boochi which is a random event.
just go to Neopia Central, then to the Rainbow Fountain.... then instructions should take you on from there.