My wife and I would love to buy an ocean-front house for
vacation/retirement someday, but we are sure that ocean-front property
in the southeast is out of our league.  Where would I find the most
reasonably priced (cheapest) ocean-front property that still has a
beach of some kind in the U.S.?  It's even OK if it's in Maine; as
long as we can enjoy it in the summer, that's good enough for us.

I'm no expert on the matter, but North Carolina has some suprisingly
inexpensive oceanfront properties.

On thing I do know is the beaches of Delaware are severely overpriced. :-)