I Need To Find Out What Is Happening

I have been with my boyfriend for about two and a half years and I suspect that he is having an affair. He does not work and several periods I stumbled upon unusual things within my house the minute I got there from work. He keeps telling me that I am paranoid, however I understand that there is much more to it than he is admitting. I think I am going to purchase a hidden camera and see if I can catch him in the act. I do not have quite a lot of money, thus I hope I could find one with reasonable quality.