Anna Marie Island is one of my favorite local areas for photos, but there my be more accommodation options just to the south on Long Boat Key, Lido Key, and Siesta Key. They all have far more rentals but I'm not sure about prices and have no websites off hand for you.
Closer to my area of Venice there is Casey Key with a few small places, don't know price or availability. Venice itself only has two motels on the water!
http://www.innatthebeach.com/ with 49 rooms and
http://www.beachcomberinvenice.com/ with just 17 rooms! Good luck with either of those! There is a lot I like about Venice the lack of beach front accommodations is NOT one of them!
I do need to get back to the Beachcomber with my camera, it's very retro, looks like the type of place the Rat Pack would have hung out at if it was in Palm Springs or Vagas.
Just to the south of Venice is Manasota Key there looks to be some more affordable places to the South end there, but I have no first hand knowledge I don't get down that way very often. That would also put you closer to Gasparilla Island. I doubt there is anything affordable there but lots of great photo ops for some old Florida style island charm. Not as colorful as Key West area or Anna Marie Island, but very nice.
David
