Is your project being inspected by a local gov't? If so, then some localities require it to have an engineer's stamp since there is nothing in the the code books for solar panel mounts (designs, requirements, etc..). That stamp is (usually) easily attainable if you buy a pre-engineered product.
I'm currently in the process of a ground mount, grid tie system, and Pro Solar was the cheapest racking I could find. Dig really hard on the internet and you can find their stuff pretty cheap. Basically, anything that comes in a box you buy from them, the rest you buy locally.
If it's not being inspected, then have fun! There's hundreds of posts of here that very accurately describe how people have done their own systems and how well they have stood up to the elements. Personally, if it's DIY, then overkill is the best way to go.
And my absolute favorite: copy someone else's design, especially if it's already engineered. You could spend a lifetime on loads, forces, calcs, etc., and never figure it out unless that's what you do for a living. A lot of time on Google can save you a lot of money on design.
Just my 2c, have fun.
