The efficiency difference isn't that much, going up a panel size might be your only option to get more wattage in this case, but look around. I'm not sure how that all works, but I've seen similar sized panels with 30watt differences, I've also seen two similar sized mono's with very different wattage, so it all gets pretty confusing after a while. Just get whatever fits
Emaineinc.com has a 135watt kyocera
for $375 (59x26"). $385 doesn't sound like a good deal for 100 watts. But I haven't done any panel shopping
in several months...