The racket goes like this - a lawyer firm, specialized in this type of "work", finds a token blind person and sends you a letter to the tune of "On date such and such, our client visited your site and it wasn't accessible. Based on such and such precedent, we're not required to give you advance notice and can to sue you for $100K. However, we're reasonable people and we're willing to settle out of court for $10K, as long as you promise to fix your site under the supervision of an accessibility expert pointed by us".

For small companies, even if you're in the right, the only thing that makes sense is to settle. Going to court is way too risky.