laptops are never worth replacing a motherboard nor the processor most laptops are throwaway after the warranty runs out. and laptops offer no upgrade path so the specs it has are what you are stuck with.... with the newer gaming lap tops going for 800-900 with gtx 950m and an ssd no one will...
why would a motherboard cost you 350? are you building a super pc that will be used for a server or heavy video editing?
even a decent gaming motherboard can be purchased for around 80-120
id say you could get maybe 350-400 dollars locally on a site like craigslist, backpage, or other local buy/sell/trade sites or in local classified ads. also try ebay.... really though everyone is going to try to low ball you but i would start at 500 and not go below 350. hope this helps
p.s...
good build but if you really want an i5 later get the anniversary edition pentium G its able to overclock and kills the i3 and is cheaper and get the 280x now. http://pcpartpicker.com/p/QvKFnQ comes in at 635
with my set up and windows 8.1 would i be able to run a thinclient for the sole purpose of streaming to my TV? if yes other than the thinclient hardware what would i need?
we mostly stream from primewire.ag i doubt our ps3 would be able to stream from a website like that. when she uses netflix or hulu she does use the ps3 but that is basically an app based program not real-time streaming.
we have 2 pc's already i do not want to put money into another machine if i can upgrade an item in mine like additional ram or an ssd or upgrade gpu if that would help.