Macedonia is 50 Euros. I found out last year. I only wanted to transit through in one day. I couldn't bring myself to pay that for one day, so I rerouted around. Bosnia let me through without any insurance. I think this was mainly because the border guard didn't speak English. He just looked pissed off and waved me through.

Travelled through most Eastern countries, Estonia, Romania, Latvia, Lithuania, Bosnia, Macedonia, Bosnia, Kosovo, Moldova, Transnistria and lived in Serbia for 5 years.
Had a small glitch coming out of Moldova once, 2 pages missing out of passport, no idea when it happened, but border guard spotted it, held for 2 hours while they decided what to do, eventually let me go saying i wouldn't be able to return with the same passport. Riding and driving into Bosnia, kosovo, Montenegro and Macedonia.

Can't remember ever having my passport stamped.

Serbia has recently become a little stricter over white paper. i.e. small scrap of paper you need to get filed in by police or hotel where you're staying, sometimes they'll ask for it when you leave Serbia sometimes not.

Ive been stopped for traffic offences, mostly speeding. Im in the wrong, I'll pay the fine..But its amazing what they'll forgive if you treat the various authorities you come across with a bit of respect and understand they may have dealt with more than the odd foreign arsehole in their time. The only place I've found this doesn't work is in the UK tick box society... and the only place I've ever had an issue with border guards is when entering the UK.

I never act like the arrogant foreigner. always smile, and don't try to bring your home countries culture with you.

If you need any advice re Serbia please ask, its a beautiful country with very friendly people, its worth a visit if you have the time. The old part of Belgrade is fabulous...