For that budget, onboard graphics and a budget i7 would likely be the way to go, the i7 is a must to get faster photoshop rendering and cut down on wait time, you will want an SSD big enough for both the OS and Photoshop, as well as any current projects, in fact it will be more important to have photoshop on the SSD, as boot times are irrelevant for a business PC you can just leave running, but the faster read/write speeds will be a big boon when editing photos, then you can archive finished works onto a larger storage drive
I would highly suggest going with 2 large storage drives internally, and striping them in a RAID 10 for redundancy, you DO NOT want to play around with losing important documents
She may want to even consider upping the budget to include a large external drive to backup the computer on a daily basis, and keep this stored off-site, that way if anything were to happen (fire, flood, etc) then all the valuable works and photos are backed up. This is also a selling point to clients "we keep your important photos backed up using triple redundancy"
You will also need a good amount of RAM, probably 8gb (2x4) to start, with an eye on more later if needed (so a 4-slot motherboard)