since no one said it yet...dont buy info on ebay etc...it just tells you to call retention and deal with them. Last fall it would have worked, but the days of cheapo hdtivos are gone, sorry. Newegg.com used to have HDtivo for 398 so try there first.
Regarding OTA, i'm sure dtv will sell you a 50 dollar OTA on top of their dish. Why wouldn't they? There's no guarantee of reception and you'll have to complain to get a refund. So it's win/win for them.
As mentioned above, getting your own antenna is definitely the best solution. Your money, your problem, your setup. And i mean that in a good way. While you are potentially close enough (and i dont think FL has hills or mountains right?) unless you get a refund guarantee from DTV, i think you would be better off doing OTA yourself.
regarding HDtivo: unless you can get in OTA well (but apparently you can), i dont usually recommend hdtivo. Waivers are pretty hard to come by if you live in a 'major' metro area so the NY feeds probably wouldn't be turned on for you.
and if you do have some vhf stations, hopefully they are all the same direction and maybe you can use jointennas and such things to enable good reception. As you know, you can't 'really' use a rotor with hdtivo.