This is a good time to BUY UP - If you wait, you may sell for a higher price but the target property will increase at generally the same rate.  But, since the target properties price is greater, the total dollar outlay will increase proportionately

sell 200K now
buy 300K now
%20 down will be 60K Mortgage will be 240K


WAIT a year
The 200K is now priced
Sell at 220k
Buy 330K property = make 10K more
%20 down will be 66K Mortgage will be 264K

You would need to finance 24k more.  Let's say 4% over 30 years - Your payments increase $114.58
/month.  Over thirty years that's $41,248 over the life of that mortgage. 

This is a simplistic model but I think you see the rationale ...

On the obverse:  No is NOT a good time to Buy Down.  Play with the figures for profit and loss and see if holding on works for you.

Regards,
Mike