YSI has a model DO2000 for approx $250.00 with a 30 ft cable or $225 w/ 12 cable.This meter is considered their Economy meter. It measures DO and temp. I have not used this model as our model 55 has been very reliable but as you state they are expensive.
I'm with Ted on that. If I had to do it all over again I would not spend $800.00 on a meter. Many times I trust a good ol' Hach kit or LaMotte test kit over my meter anyway. Even with calibration, membrane change etc. my YSI is reading about a half a part ppm too high compared to the Hach or LaMotte test kit. I may have bought a lemon. Of course you can't test the water column all the way down with a Hack or LaMotte test kit.
Not sure what others think but I would seem a Hach or LaMotte test kit would be all you need to test for D.O. drops in an ice hole. If D.O. is less than 6 ppm in your hole it may be time to crank up the diffuser.
Here's what I use in conjunction with my meter:
http://www.aquaticeco.com/subcategories/2805/LaMotte-Test-Kits-Dissolved-Oxygen 
