Why do you need an actual RACK?
4x (6x if you want belt and braces) pad eyes and trifold rivets - it is what is used for rigging sea kayaks. If you want to ride over I will do it for you. Buy me a beer...£50 is a lot for what you can carry on the lid and pad eyes will do the job quite happily. You can lift the entire kayak up by one, the fitting is that strong. You MUST use trifold rivets though - or washer backed bolts, but the saltwater corrossion resistant rivets have lasted for 10 years in saltwater on my old kayak, so they are very secure and long lasting. It will take me about 10 minutes to fit them for you - and they won't leak either because I will seal them.