A premium plan for Dating Site Builder retails at $29.95 per month.
Their small business plan retails at $49.95 per month and offers additional features such as webcam chat and matchmaking.
For example, in the UK there are always adverts for uniform dating websites.
And who knows, perhaps you could go down the freemium route and develop the next Plenty of Fish.
The software uses PHP and a license will grant you to the full source code.