I really liked this blog post 8 by Emil Wallner, lots of good information there including some good insights on current hw options (will probably change in a couple of months)
Emil makes a very good point why a home rig is the way to go:

The main reason to own hardware is workflow. To not waste time on cloud savings and encourage robust experimentation.

I would also recommend this hardware guide 3 by Tim Dettmers. It is the definitive resource with timeless answers to many questions 
Two observations from Tim Dettmers’ guide worth highlighting:

the number of PCI lanes is not as important as it seems
RAM timings are not important

Both of these points above can save you a lot of money.