Actually, the game has changed! The cheaper solutions are (and have been) available for the E-500 forat least a littlewhile now. Try this link:
VirtualVillage USA on eBay
Their prices went up -- it's now $30 + $7 shipping (used to be mid $20 with free shipping or something similar), but that's still significantly cheaper for split focus screen designed specifically for the E-500.
Dozens of reputable people on other forums (DPReview for one) are recommending them without reservation. I'm getting one based on those recommendations. I will come back to the thread and post a little review when I get it.
Although the E-500 isn't designed for quick changing of the focus screen, it's relatively simple and non-instrusive to do.
Just a bit more information on pricing -- if you go to the Virtual Village Australia eBay store (instead of the Virtual Village USA store), you can get the split focus screen for the E-500 for about US$25 + $4 shipping, so you get a little bit better of a deal by going through the conversion of Australian dollars. All products are still shipped from Shanghai, China.
Here's the direct link to their Australian site:
Virtual Village Australia
Just FYI, I'm not affiliated with these people in anyway other than being a very recent customer. Again, I'll come back and post my experiences with their product once I receive it. So, if you'd rather wait to see how things work out for me, I should be able to tell you in 10-14 days.