I'm an auctioneer in Arkansas and I know that if I sell at an auction house on consignment I will have to have a sales tax permit but is this the only time I'm required to have one?

Contact the Arkansas Tax Department (see link below).

DFA | Excise Tax | Sales and Use Taxes Overview (http://www.state.ar.us/dfa/excise_tax_v2/st_index.html)