I want to build one for fun too but main reason is for profit. The more profit the more fun. That is just simple math here. Yet actually doing it is the hard part. Each passing day I do not go out and take a leap I will only feel I am missing out and the higher the difficulty.
37.1MH/s on 3x1050s actually sounds decent. I am likely going to pay more for new cards because I just don't trust the run time on the used cards. I have read many bad stories like the miners that were built and resold burn out in a few months because they were running of fumes. Resale values of those are likely dropping or will drop due to usage. I have been on ebay for two weeks and the rig prices are still ridiculous. Going to wait even though difficulty is on the rise.