Well, it'll be mighty difficult :)

Personally, I don't have any, but I know of a 
couple places that do. Whether you can actually 
get them to trade/sell them is a different matter.

http://iwantpurplehair.tripod.com/

and

http://members.home.net/mirainotrunks/

Also, you missed a couple on EBay in the last few 
weeks, but occasionally one will come up.

As you know, these cels sure are expensive. I 
have about 8 cels of other characters and 
combined they aren't probably 'worth' as much as 
some of the Majin Vegeta ones.

Good luck :)