Wayne's list gives a good idea of what is involved in the THX certification process. It also gives you a good idea of what is involved in designing a receiver or processor (or even an amp), and just how expensive it could be to have a third party like THX "check your work." The larger companies (like Pioneer or even Denon) can afford it because economy of scale works in their favor - a THX-certified product that they bring to market will sell so many units that the THX licensing fees get spread out a lot and have less impact on the price of that product. Companies that operate at a different sort of scale - ones that sell through specialty AV dealers (Rotel, Sherwood, Adcom, and others) or online (Outlaw) can't expect to sell in the same volume, and so the licensing cost has a much greater impact on the list price of a certified product. The result is that you have some products that are designed to come with heftier price tags to begin with (Anthem's processors, Parasound and Halo processors, Lexicon) incorporating it into the price and other products that elect to omit THX.

The reason that many folks in this forum (and other online forums) tend not to get particularly worked up about the omission of THX is that we are doing a bit of cost/benefit analysis. Can we find products designed to a high standard such as THX describes without relying on the familiar THX logo to do the looking for us? Yes, we feel that we can. Do we give up the THX processing modes that would be included on a processor or receiver sporting that logo? Obviously so, although that only applies to receivers or processors - THX certified amps or DVD players don't offer anything more than the quality assurance aspects of THX. Are those processing modes worth the extra money when we still have tools such as Dolby EX (which THX EX is a close cousin of), DTS ES, or Pro Logic IIx to make use of? That's a personal choice, but many of us (including myself) don't feel that we are losing anything by sacrificing the THX modes.