Pretty much *any* tire gauge, even the dirt cheap ones are plenty accurate and have incredibly good repeatability (especially considering how simple the mechanism inside is).. The biggest difference I see in a cheap gauge vs. an expensive one is the quality of materials used, especially in the sampling head (the part of the gauge you apply to the tire valve)- good ones seal perfectly every time and don't let much, if any, air escape when you apply/remove the gauge; with cheap gauges, you can lose so much air applying/removing the gauge that the reading is useless..
Now the digital ones are really not worth it IMO- when I first heard of them I thought that someone finally invented some sort of miniature direct-reading pressure transducer based on a strain gauge or a piezo element or something, but if you look up the patent number, these digital tire gauges basically use a mechanical movement that translates pressure into linear displacement, and the amount of movement is digitized and converted back into a digital pressure reading (ie, basically, they've miniaturized a regular mechanical pressure gauge and slapped a digital interface on the back end).. Additionally, the digital reading is only good to +/-1 PSI on the cheap ones, and even the most expensive model only reads to +/- 0.5 PSI, so for example, you'd only ever get 38.0 and 38.5 readings, but never 38.3.. The last strike against digital tire gauges is that the majority of them have really cr*ppy sampling heads- they leak like a sieve unless you happen to get them onto the valve stem just right..
If you're going to spend a bit more, your best bet is a good quality dial-reading gauge, but otherwise, as I said, pretty much *any* gauge is going to be good enough.