Refurbished motherboards cost around $200 and up from Dell. You can find other online sources for refurbished boards but they start at $100. Replacing your own caps will cost you under $30!
If you are familiar with soldering (I hadnít done it since college) it is not a hard job and should take about an hour for your first one and will get quicker once you do a few. You donít need an expensive setup, I still use a $15 45Watt soldering iron and $3 bulb sucker from Radio Shack and have never had a problem.
If you want to dnate your old equipment Freecycle