Well, I can't find anything cheaper than $340, but I'm wondering what the optimal date of departure would be for you. The 12th seems fine if you only mean to get there right before Valentine's Day, but there are also many flights available at the exact same price that are departing much earlier. As of right now (the time of posting) there are one-way tickets from PDX to Caracas available that depart as soon as January 21 for only $340 as well. So, theoretically you could arrive in Venezuela as soon as January 22 in the afternoon at the same price as you would pay for the Feb. 12 flight.
Granted, at only $340 all these flights will be two-stop over-nighters, but they'll get you there nonetheless. You may not find it convenient to leave earlier than the twelfth, but I thought I'd mention that it doesn't necessarily need to be that late of a departure date for the $340 price, in case you didn't know.
Well, that's all I've got for now, but good luck on your further searching! If I by any chance do find a cheaper airfare, I'll be sure to tell you, or more likely tell Say, since I've yet to make any contact with you at all.
