Yeah, I couldn't decide what I wanted. My parents offer me the option of having that $150 in a check but I always prefer having something to play with on Christmas.
You have a couple options. You can either set up "calculated" shipping where the buyer enters his zip code and depending on the service provided (UPS Ground, USPS Priority, etc.), it determines the approximate cost of shipping. From here, (at least on Auctiva) you can specify an amount of money to tack on for a handling charge. If you want to specify your own shipping charge amount regardless of what it typically goes for, you also have that option.
I do my selling using Auctiva. It's free and provides a lot more tools that you get free through them that you would normally pay for through setting up an auction directly through Ebay.