If someone is looking to get a tablet without blowing their budget, I recommend those sold by Monoprice. I've worked with Wacom and I prefer the Monoprice. For about $50 you can get a 8"x10"...
You don't have to move your whole site. Instead you can install Wordpress in parallel and link to its gallery. Your client will have an editorial acces to that ecosystem while you'll retain full control on your website.
It sounds clunky, but it would work as a stopgap until you can roll your...