you can wait a month and order this an external t-bolt ssd.
this one is also coming soon
Keep in mind that the BTO iMacs with SSD are specially made and have a bit more room.
I have heard of people having trouble with SSD installations because of this. It is possible, but just more difficult.
Well I was reading a thread on here where a guy went to an Apple certified technician and they tried to install a certain SSD and failed. They didn't charge him and he returned his iMac and bought a BTO one online. He measured both and said there was a little more room on the BTO one and seemed very confident in what he said.Whaaaa?!?! This is news to me and also the most farfetched thing I've heard on here since 7pm tonight.
An expert lol, you mean a customer service employee making less than $12/hr to take an order.I bought a custom iMac, but had to do it over the phone. Use the number on the Apple site (top left of the screen unless the have moved it) It's better to talk to an expert when speccing up a Mac.