Well BigAl's usu. has good prices on most items,might check there. I picked mine up at lfs.
A 14-day feeder ran $30, a Nutramatic digital cost me $50...there's prob. cheaper.
Some w/ separate compartments for each day, some not.
Can't vouch for performance, tho I think the digital would've been fine. I had decided not to actually attach it to the tank--came back to find it had tipped over the first day.
So whatever you decide, I would test-run it maybe a week before.
Flake could be a problem, might stick w/ humidity/evaporation. I had set mine I think for one pleco-tab a day..I know the other fish go after 'em..and I figure a little less food is better than a little too much.
On the vacation blocks, I'd heard ways back that they have very little nutrition, mostly chalk. But maybe for a week, it'd be worth it..or maybe they've improved them.