1.4 L and then you have to pay duty I believe, so just 2 bottles -- but just make sure to get the receipts and have them state clearly that they are PESOS not confuse the $ with being dollars -- if you're lucky you'll get away without paying much, with a wink and a smile you may get by without paying anything!
As far as wines go -- 10 pesos these days isn't getting a wine that's worth taking out of the country -- remember you also want to avoid the extra weight charges, which could be a lot more than the wine is worth!
For 20 - 25 you can get some decent ones, in that range we've been drinking a fair bit of Uxmal.