This is not a bad source:
boat for sale
Also, once you have found a listing that you like - on Yachtworld, or another site - but it is a bit out of your range, watch it and see how long it sits on the market. Boats will start to get cheaper towards the middle/end of July. The prices that are posted will not change, but the vendors will become more flexible as it starts looking like they' be paying for haulout and storage for another season.
And don't be afraid to call someone up and tell them you have a budget of a certain amount... even if they are asking double, they may be willing to come down if the boat has been on the market for a long time...
Keep checking listings and tracking how long the boats have been for sale.