Hello! Do you want a solution that can be placed on your server? The specified budget is too low, but I can recommend you a cloud solution, the cost of which is lower than the cost of using mywifinetworks
I am one of the developers and ready to help integrate your access point.
Tell me, can you be interested in this?
UPD: I saw your message in the chat, but could not reply because when you write a reply, the error " Failed to send. You do not have permission to message this user." occurs.
Write, please, how can I contact you?
Thanks!