Fair enough stratus_020202 , sorry OP. A good cheap analogue type
http://www.amazon.com/Western-Digita.../dp/B0007VWEQA
http://www.amazon.com/HygroSet-Adjus..._bxgy_hg_img_c
The digital one isn't bad the temps are not great but no cheap digital one is great anyway. The problem I found is the adjustment for % humidity is very easily moved and the snake may make changes for you.
The thing to keep in mind is what is the deviation possible with the digital thermometer, for example a pro exotics PE1 IR gun is accurate with in 4º (2º over correct or under correct) So if it reads 93º the actual temp could be 91º or 95º which is on the high side. Good digital ones are very very expensive (better than 0.5º+/- is over 300$ typically and as much as 2000$) Just plan for the range so typically I'd never set any hot spot over 91ºF and not under 77ºF I like 80/90 and then judge the temps based on the animal, if it always seems to be on the cold side drop the hot side by a degree, If always on the hot side raise the cool side temp a degree.
I have found that they like different temps I have set as high as 91/82 and one as low as 88/78. Keep in mind small snakes generate more heat when digesting than larger ones do and they can raise a hide by 2 or 3 degrees, my coolest enclosure is the smallest snake. They (all of mine) seem to spend about 80/20 cool side to hot side. Typically the hot side after a meal and some mornings (really cold or particularly damp ones)
The upshot of all my digression (sorry for that) is check the specs of any and all instruments and keep in mind the listed range when setting your temps try to balance the top and bottom of the range to be with in an acceptable temp.
I was asked to look at a snake that had been burnt by no fault of the keeper just ignorance he had set the temps to 93º (thermometer was really bad and low by 3º) the T-stat had a 6 degree range and he had heavy plastic dog bowl hides.
93+3+3=99 and then a well insulated hide allowed yet another 5 degree temp difference... 104ºF and given time that will cause a burn. Check inside the hides for temps it can be quite different inside compared to outside. and pay attention to the specs of all the devises and test things out as much as you can before you add the snake to the mix.
Alex