Ebay has always been a good place to find items like this....just be sure it has a warranty and the seller has 99% or better feedback rating, and that the shipping rates are realistic....Sometimes a board is only $70 and then the shipping is $50.00 etc... Anyone urgent to purchase might click BUY and then say great I just paid $120 for a $90 motherboard elsewhere and get ripped off by $30.
I never made that mistake, but I am sure others have...especially items for a penny or dollar that are way under priced until you see the shipping brings its cost into check with what it should cost or even more than you would pay elsewhere.