Try a Mini or Small toy from Bad Dragon, they have quality products. Browse the existing inventory for "Flops" that look enticing to pick something up on the cheap. A blemish can sometimes cut the price in half without much difference other than aesthetics. You will also receive the toy in weeks instead of months it takes to do a custom order.
Anything less than 5.5 usable inches in length and no more than 5 inches in circumference at the widest point is probably good to start with without damaging your hole. Remember to go slow and use lots of lube, don't feel like you need to take the whole toy at once the same day it arrives. Maybe play with your entrance using just the tip for the first couple of sessions.
A suction cup is highly recommended. Have fun!