Ties dont have to be so fancy as what aftermarket offers. They're over engineered in my opinion. A few pieces of about 1 inch wide flat bar will serve the purpose and not as likely to collect gravel.
I've made my own stiffening plates, but at around $25/pair for aftermarket they are worth it in my opinion. NOW, if I had a plasma cutter or a CNC water jet, I'd make my own...
