I never make offers.  There's just too many 
variables and unknowns, and the prices of cels is 
too variable.  I don't feel I know how to 
formulate a proper offer, so I don't.  No matter 
how badly I want a cel, I'll wait for a similar 
one to come available at a fixed price or on 
auction.  Many people did not sell me cels that 
that probably could have, because they wanted 
offers.  (I actually broke my rule once and made 
an offer on a cheap cel, because it was a cheap 
cel, but that worked out so poorly that I won't 
be doing it again).

If you go to eBay, I'd also recommend against 
doing a reserve.  I and many people resist 
bidding on any auction for which there is still a 
reserve price, because we don't like bidding 
against the unknown "reserve counter-bidder".  
There are many auctions I did not bid on because 
there was a reserve price (I definately do make 
exceptions to this, but I have to REALLY want the 
cel).

Reserves have cost people in a different way.  
The was a KNO cel on eBay last November, which I 
bid on in spite of the reserve.  I was the high 
bidder, but I did not reach the reserve price, so 
the auction ended with no buyer.  A couple of 
months later, the cel came back again, with a 
reserve price again.  This time I did not bid.  
Someone else did, and they won;  however, the 
reserve price (and winning price) on the new 
auction was 30% less than my original bid!  Put 
another way, my original bid was 50% higher than 
the winning bid!  The reserve on the original 
auction cost the seller quite a bit....

NEVER, EVER setup an auction with an 
unrealistically high "looking for a miracle" Buy-
It-Now price combined with an unknown reserve 
price.  When people see this, they assume that 
the unknown reserve is also unrealistically high 
and they just don't bother.

I've had very good luck on eBay.  Pick the lowest 
number you could be satisfied selling the cel 
for, and make that the opening bid amount.  Pick 
a higher (realistic) number that is your "happy-
happy-happy price that someone would pay on a 
really good day", and make that the buy-it-now 
price (but keep it realistic).  Re-list it once 
if it fails to sell the first time;  if you don't 
want to drop the opening bid on the second 
listing, increase the Buy-It-Now price $5 - $10 
to telegraph to watchers that the price will not 
be getting reduced.

So far, I have failed to sell only one (friggin') 
cel using this protocol.