Their product is probably as good or better than what you are doing. Sorry, online sites like this one do business in bulk with more man power and equipment than most small shops. I'm sure their order process is streamlined also, so when you are arguing with your customer about prices this site is taking orders 24/7 with no intervention/hassle, customers designed/uploaded art online, queuing jobs to print in bulk, boxing and shipping out the door.
While on the surface this appears to be a fly by night web company it is buildasign.com(one of the bigger sign companies online) re branded with cheaper pricing. You'd be surprised how few "big" players there are online selling various products under different domains/price structures.
