Flash tends to be the most popular and expensive dragon - I would ask $50 for him.
Lightning will normally be the $70 mark; it depends how bad the symbol flaws are as to price - if its just a little scratch or 2 then perhaps $5 less if its significant rubbing then he could drop $20 as when people are spending a lot of $ they understandably like ponies as perfect as possible.
Tex with hat - $25
Salty with hat - $30
Barnacle with hat but with hair issues (Barnacle is a little prone to hair issues due to the original curl in his hair) - $40 (assuming no age marks and his hair can be fixed)
NSS Cupcake - I would auction rather than sell - $90-100 for her minimum probably.