Well .... I did read actually. To make my point I just underlined the prices from the sites you mentioned. Notice it is in RED so that you can see it.
Go on
www.ebay.com.au and look for "Yongnuo YN-468 II" - it's a reasonable flash WITH E-TTL. It has a 33 GN and it costs $89, handling/shipping included.
I completely believe the OP will be much better off with a 1100D + kit 17-55 + 50 1.8 + sub $100 flash WITH e-ttl + time to try to do some shots than with some new stuff, than with some new rented gear he hasn't had time to get comfortable with.
Why rent a low end camera while already having the 1100D anyway? It doesn't make sense either.
The OP also already has the kit
lens, did you read? While it doesn't have a fantastic image quality or super wide
aperture, is a 17-55 which is equivalent in angle of view to a 27-88mm on FF.
Everything seems very out of context. This is going nowhere. I'm out of here.