FInishing RI30, what next?

I've just started week 4 of Jillian Michael's Ripped in 30 which I started after finishing 30 Day Shred. I really like the 30 minute workouts as I can get them done first thing before work.

Any suggestions as to what I could do next? I've been debating buying her Body Revolution for a while but it's expensive and keeps going out of stock on Amazon - are there any other short workouts I could try? I like the idea of working out for a shorter time but more regularly.

Thanks!