If you decide to go for the Metzlers you might want to give these guys at Southwest Motorcycle Tire a try;

http://arizonamoto.com/Merchant2/merchant.mvc?Screen=SFNT&Store_Code=SWMT

They don't seem to do a lot of Avons but I just priced a set of Marathons for my Trophy from my dealer;
Front $142 Rear $202

From Southwest;
Front $95 Rear $118
Even a deal on mounting can't make up for over a $130 difference. Plus if you order two they don't charge you shipping and if you're out of state no tax either

Keith