If you have enough money to keep a single developer on staff, you have orders of magnitude more budget than it takes to license a copy of Burp Suite. Burp is the de facto pen testing industry standard, and it's a fantastic QA tool in general. If you have a product and you don't know about Burp, you should buy it pretty much immediately.
P.s. no you can't have a copy of Scanmus P.p.s if you are really curious just Google the name
Disclaimer: I still work for Y! :) and I'm proud of our security guys
P.p.p.s no that wasn't a challenge