Thankfully around here a lot of the suppliers know me because my Dad was one of their good customers. Others will deal with me on the strength of my business registration. I deal "cash only" - no account
- sometimes with my credit card. I don't get the BEST price but I do get a reasonable discount from list from most of them. The invoice will often say "cash contractor" or "wholesale desk" - accaisionally cash and the name of someone I know.
A/C and Natural Gas stuff is a bit harder because I don't have a refrigerant handling number or a gas-fitter's licence - but I can have my Hvac buddy call in the order for me if I'm stuck, or just call in a favor from a nephew etc.