Some advices before searching for accommodation:

• 
  Night sight of one of the channels in Venice
  Avoid booking accommodatons where it seems the rooms are humid. The not restored buildings in Venice are very untidy. Damp bedrooms are very unpleasant, because they also can smell a little.
• Some accommodations offer you rooms with views over the channel for a superior price. Sincerely, if the views from the room aren't really incredible, book a room without views. We booked a room with views and payed 15% more, and wasn't worth it: it was a secondary channel which smelt a little. Moreover, you'll be more calm.
• If it's a central hotel, it doesn't matter. As we said, you can reach any tourist point in the city by walk, and you can benefit from the walking.
• Some hotels seem to be in Venice city, but they really aren't. They are cheaper and are very near from the city. If you want to lodge in Venice, be sure that the accommodation is in Venice island. It's worth it.
  
  

Finding accommodation for a reasonable price:

The accommodations in Venice are not cheap, but searching a little you can find interesting prices. The most comfortable is booking in an on-line booking website, as they offer cheaper prices than the official rates published in the hotel website.

It depends on what you are looking for, but the cheaper accommodations in Venice can cost you between 30-35 € per person and night in a double room. With a budget of 60-65 € per person and night you'll be able to find good hotels, in tourist areas, with buffet breakfast (strongly recommendable).

The price between high season and low season also varies, but not much.