Sell some and if it goes higher sell more?
My guess is on this unamed marketplace you needed a certain about of USD. The BTC are now worth more than that USD value. As an example lets say you need $500 and the BTC is now worth $800. You could sell $500 worth of BTC as a hedge, then let the remaining BTC ride. If they go up significantly more you could sell another $250 worth and let the rest ride.
That's a good idea.

At the current rate, even a small portion of my still-frozen BTC (thanks a lot MtGox

) could cover my needs on this marketplace (I only have interest in a few lower-cost items so I'm thinking about $100 should do me good).