It depends on what you mean by "near the reservoir." There are homes that are walking distance to the north end of the reservoir that are relatively rustic, and don't come on the market often, and they go for between $200K and $300K.
Then there are homes in Horsetooth Lake Estates that are relatively close to the reservoir, but are on the west side, and these homes can be just about anything, from a mobile home to a million dollar mansion.
If you're looking for a waterfront home, I don't really know of any. And lastly, most homes in Fort Collins are within about 15 minutes of getting a boat in the water, and you can find anything you want in the city of Fort Collins.
What are you looking for?