Storage Payment Pros
Company is a merchant services (credit card) sales organization exclusive the the Self Storage Industry. Therefore, a logo that projects strength, stability, integrity is required since the company is dealing with credit cards.
Not looking for any "cartoonish" clip art of credit cards or credit card machines attached to the logo. In fact, many times a unique font and color is all that is needed to appeal to us. Adding a design symbol is okay, but once again, not cartoonish clip art.
Credit Card Industry/Self-Storage Industry
A strong and unique font, coupled with good color, and maybe a simple design symbol (or not) should do the trick. (A box or square design symbol preferred since it will resemble a self-storage unit).
In fact, something similar to the 99designs logo may do the trick. Go for it!!!