I have a Retina iPad (16GB AT&T).
If this is $199, I'll buy an extra just because, really. If it's $249 I'll debate. If it's $300 - screw it, I'll get a Nexus 7 to toy around with.
My prediction for the event, which unfortunately on many cases doesn't line up with my hopes:
8GB iPad Mini; iPad 2 res, A5X, 1GB RAM, Lightning = $249 (plus additional sizes for more)
"Refreshed" Retina iPad = Lightning connector, slighter better battery life/less heat for same price
13" Retina MBP - i5 Dual Core, integrated graphics, retina screen, 4GB, 128GB SSD = $1499
iMac - 21" and 27", redesigned, with retina display on the "high end models". High end models will be $1499 for 21" and $2299 for 27"
My hopes that ares till somewhat feasible but unlikely?
iPad Mini 8GB for $199. Same specs as above. But comes in colors.
13" Retina MBP comes with dedicated GPU and 256GB SSD with some awesome 8 hour battery life - $1499
27" Retina iMac comes with a decent dedicated GPU and is priced at $1999.