The other cheap alternative you could look into would be this:
Get three 2 liter soda bottles, fully intact. Fill them up with whatever water you usually use and then use a pin to prick maybe one or two tiny holes in the bottom of the bottle. Just set the bottles in your pots, next to your babies, and they'll slowly leak water out into your soil and keep it moist. It's not ideal because you won't have the wet/dry cycle, but it's really cheap and easy and should work well.
Lastly, set it up a few days before you plan to leave so you can get a feel for how fast the water is releasing. This system in combination with a soaking up system would probably do you just fine. Just refill the bottles on your single trip back. GOOD LUCK!