I like it!
The engineer in me is really digging the 200-entries-per-raffle scenario, with each entry yielding a 1/200 chance of winning a $4k painting by Graig. (That's better odds than most modern card packs, isn't it?) Those numbers would round out nicely, with each entry getting exactly 5 numbers, which would also make it easier on whoever is keeping track of all this.
Hopefully the response will be overwhelming, and we can make this a regular event! Maybe Graig will even get to paint someone besides Mantle or Ruth