Unfortunately homes in the $450k-$500k aren't selling very quickly. Right now the focus is on homes suitable for first time home buyers since they can take advantage of the tax credit that is being offered through April. That's not to say if won't sell and can't sell quickly depending on the condition, price compared to other similar homes on the market and location.
You're doing the right thing by planning in advance and seeking the advice of real estate professionals.
or a What's Your Neighborhood Worth?