Here’s a comparison I did having owned an e93 and e90.
https://www.bimmerpost.com/forums/sh...php?p=28701661
Would not purchase an e93 for the cost benefit. As they age you’re looking to replace around $4k US in rubber seals and rear glass and that won’t include any repairs to the top mechanism. I suspect this will make up for any cost savings up front.
I do think the e93 is a great car on its own right, hard to find a four seat convertible better. It is not a purpose built roadster but I wasn’t looking for that either.
If I did my e93 journey over I’d put my modification dollars toward an exhaust and a carbon fiber plenum.