Meanwhile, even with the recommendations that don't involve dropping an aftermarket cooler, there's a solid $100-250 to be saved, though some of it would be contingent upon Microcenter. The current Intel HSFs are almost comical, with how small they've gotten, and any i5 or up definitely will buzz/whine just as much as they ever did.
Cooler: $20 can be saved easily by going with Thermalright, at no cooling disadvantage at all. The Macho 120 will fit with room to spare in the Define Mini.
Mobo: seems $20-30 more expensive just to have a switch or two that can be accidentally pushed.
i3 v. i5: depends, but Lightroom and PS would get a boost from an i5, and there are likely other programs the OP will use that will, too.
i5 v. i7: all want. I've got the Xeon E3-1230V3 at home, and the difference w/ HT is sometimes non-existent, but sometimes nice to have, and quite apparent. It's nowhere near worth sacrificing other parts for, but if the budget isn't so limited, whatever. It's more than the OP needs, though, and is going well into diminishing returns.
SSD : pure want, but something the OP is set on. I've got half-TB ones, so I can't say too much, there . Still, I'd get the Crucial. It's cheaper absolutely, cheaper per GB, and Crucial's consumer-level support is generally very good, should anything go wrong in the warranty period. It's also important to understand that benchmarks generally are made to try to push the hardware. Yet the reality of it, more often than not, is that the human in front of the computer, and/or the software being used, will typically present more of a bottleneck than the SSD.