I'm trying out this gal who does all kinds of personalized logos on signs and such. I think she'll do a good job but I haven't gotten my first products from her yet so I don't want to make a recomendation too soon. Should have my stuff by R Nationals.
She's supposed to send me some cards of hers to hand out there.
Other than that, I'd say do what Lyn suggested and just search the internet. I found several options out there.
As far as the horse pulling the cart design. I like to create such things from photos of my own horses so that nobody claims I stold their design.