I completly aggree with you, i had an acer aspire 1300 last year and the dc socket in the back of the laptop broke. I looked inside the laptop myself and all the parts are so flimzy and easy to brake. I spoke to acer and they said £300 for a new mboard. What model acer do you have?
Depending on exactly what has happened it may be repairable without renewing the mobo.
Plugging/ unplugging can cause the DC jack socket to come loose on the board and a resolder job plus a bit of superglue can fix it the repair is easy enough. The hard bit is stripping the laptop down to get at the board and then putting it back together again rather time cosumming, thats why the cost is so high.
Check around for other repairers and get some more quotes. "Another problem is broken power pins . Sometimes the laptop power lead is pulled very hard and the pin at the
back of the laptop breaks off . This can be repaired easily.
Broken power pins adapters can be repaired but as these are cheap you may want it replaced. We love component level repairs no job is too difficult." from click here