iPhone 3G Unlocked or Locked?

i buy/sell/fix ipods n stuff

bought a "broken" Black iPhone 3G 8gb from my friend today for $20
took me like 15 min to fix it and now its perfect

any whoo, i sell all my stuff on ebay and as im listing it i see that i can sell it as either normal (Locked)
or (Unlocked)

i can Unlock this thing no problem

i really didnt think that it would affect the price but apparently unlocked makes it sell for about $45 more

so im wondering.....

as the general public what are you guys opinion????

thanks