99 Windstar VSS

I have a 99 Windstar that has had the "O/D lockout" indicator flashing on,
with troubles shifting out of 1st gear. My local Autozone scanned it as
P0720. The local Ford dealer quoted me $300 labor & $60 part plus tax to
replace the vehicle speed sensor (this in addition to $112 already charged
for diagnostics).

The van is still sitting at the dealer's - I told them to hold off on doing
any work, because this price seemed way too high to me. I'm not a skilled
mechanic, but I have the shop manual, and unless I'm missing something, it
doesn't look like this is a real involved job. The 95-98 Haynes manual said
the crossover pipe has to be removed, but the specific 1999 Ford shop manual
says nothing about having to drop any exhaust components. I talked to a
local transmission shop and they said they thought the whole job would be
around $225.

Is the dealer trying to hose me? What would be a reasonable charge to pay a
mechanic to replace the VSS? Thanks for any advice you can give.