I agree with the votes for Casa Marbella if you're looking for the cleanest, nicest place in town, but it's only about half your budget, so don't expect luxuries. See if you can rent one of the new upstairs rooms, as I've heard they are far superior.
The only lodge that is really within walking distance to the village is Mawamba Lodge. They have a decent breakfast buffet and can also arrange transportation from San José, but I honestly think the prices are a bit steep for those services. I'm not sure if they offer just room and breakfast through online booking, but if you are coming to Tortuguero on off-peak days, they will most likely have rooms available and you can book directly at the reception. They are guaranteed to be fully booked during Easter week and in the months of July and August.