Home Away

I've had very good luck this past week with HA. Found a lovely house right in town, near everything we want to reach quickly in our few days seeing Guanajuato, MX.
Exquisite Home in Downtown Guanajuato... - HomeAway Guanajuato
We negotiated a slightly lower price as it would only be 3 of us and it was available between long rentals. Can't wait to report. HA does not charge extra fees like similar sites. Owners have been pretty quick to respond. We're dealing w/Santa Semana, so we feel fortunate to get this one.
Make sure to compare all similar sites: surcharges, insurance, optional pay guarantee, cleaning fees. I used PayPal for the deposit so it was convenient and safe.

Love both Home Away and it's sister company VRBO. I have never had a single problem with them and, like you, have been able to negotiate a lower rate when booking at the last minute by contacting the owner.