Try the refund first. Did you pay with a credit card (even if it was just the deposit)? You may be able to rope Visa or the like into the dispute. Major credit card companies may offer some protection -- you may need to call the credit card company or really, really scour their website.
Getting a refund is always cheaper than suing. If they don't give it to you in a week, go to their place of business and ask for it there (ask nicely, don't be a jerk; you don't want to get hauled out of there by the cops). It's best if you're there when they have other customers. They really, really don't want you blabbing to their other customers how badly they screwed up.
Don't leave without a check. As in a check
, not a credit.
No $ a week after that? Then start setting a lawsuit in motion.
And I don't have to tell you that a lawyer who represents him/herself has a fool for a client. Throw some business to a junior member of your firm and have them handle things from that point on. But first, try one last time to get a refund. As you undoubtedly know, it'll look better in court if you did everything you could to avoid suit until they absolutely tipped your hand.