I buy all my pH meters & supplies from eSeasonGear
They have free shipping on orders over $19.
I don't recommend going any cheaper than the pH-56 or the MW-101 they both sell for under $75.
These are both decent meters but as far as inexpensive that's hard to say without knowing what you consider inexpensive.
If you do want something cheaper, you can get the pH-55 for under $50 and it will get the job done. However it only displays 10th not 100th which means you won't know if your pH is 3.40 or 3.49 you will only know it's 3.4.
The eSeansonGear site gives all the spec's and has all the other supplies you will need to calibrate, clean and store the meter. Even if you don't buy from them it's a good place to compare meters.
I shoot for between 3.0 and 3.6 with whites on the lowers end, reds in the middle and fruits at the high end. 100th is a nice to have but not a must have for the beginner. I always say any pH meter is better than no pH meter.
I will add that having 100th make it easier to make small adjustments and to see what you are adding is doing something to your pH reading. What I mean is if you are at 3.39 a meter that only has 10th will show 3.3 so if you want your wine at 3.4 and add enough calcium carb to lower the acid and raise the pH by 0.1 you could over shoot and end up at or very close to 3.5
All I can say is, I'm on my 65th batch of wine, and have yet to test the pH of any of them. I brew to taste. People keep telling me I need a meter, and I still keep wondering why.