The original topic was lost when the forums went down, I'm just reposting it since it was supported by many, and i dont want it to be forgotten.
Some command like /selectpaint to allow the buyer to preview paint colors before paying money. When the desired color is found, /buypaint to pay for the paintjob and have it permanently applied.
Something similar to /selectclothing and /buyclothing which freezes the player to prevent them from leaving before paying for the changes. /rejectpaint to cancel and unfreeze like /rejectclothing
The same system could be used for /buyskin as well, many new players waste thousands of dollars browsing skins until they get the one they want.