I have an ICD-MX20 which I don't think is made any more. They were around $250 but were always availablee discounted. I have recently picked up a few used ones off of eBay at reasonable prices as backups for when mine eventually dies (it has about 4 years on it already).
Here are the specifications I see on the ICD-PX720
* Records in the widely supported MP3 format. Your recordings are ready for podcasting and can be played on any MP3 player — no conversion necessary.
This is fine. The earlier Sony's recorded in MSV format so required conversion on shops where I was to submit the recording.
* 1GB flash memory for recording time up to 288 hours (in long-play mode).
This is a nice amount of memory. You will not want to record in long play mode as the fidelity is not as good, so select less hours at higher quality and clear your recorder once you have saved the files you want/need.
* Supports stereo recording. Use either an external microphone (sold separately), plugged into the stereo microphone jack, or the built-in microphone, which has adjustable sensitivity.
Ok, so here is your option for an external microphone. I understand that Radio Shack has some external microphones at a decent price. My original microphone was a Sony ECM-CS10 3.5mm stereo Business Microphone that set me back $50+. When it died within the past year I picked up a handful of them off of eBay at about 99 cents each with $10 shipping from Taiwan. They look real, they work just as well as my original ever did, but they have to be knock offs. They will not combine shipping as they are making their money out of the fee-free shipping cost.
* Voice-operated recording for fewer silences. Makes more efficient use of storage space. Recording stops at silent pauses and begins again only when the microphone senses sound.
This is potentially dangerous, especially if you plan to measure elapsed times with your recorder. I turned the Voice operated system off on my machine because I want to control the on off with the buttons on the face of it in my pocket.
* 5 message folders let you organize your recordings. Plus, file protection function protects against accidental deletion.
Since your goal should be to get the recordings OFF of your machine ASAP, this feature is not very useful.
* Large front speaker for great sound.
You want to read your instructions and have the replay volume virtually off while the record volume is high. At one point I hit the wrong button in my pocket and began replaying my interaction with the teller while I was going in to talk to the platform person. I hit the stop button fast and started a fresh recording, but it was hard to keep a straight face.
* Includes batteries, USB cable and digital voice editor software (PC compatible).
This is the key stuff! The USB cable is what connects your recorder to your computer and that digital voice editor is what allows you to jump around on the recording with a slide bar or arrows for quick repeat of the past few seconds or a few second at a time jump ahead.
As for batteries, get a couple of sets of rechargeables so that you always have a set on the recharger to install before you head out and if you are going to be gone a substantial period of time you can throw an extra pair of charged ones in your pocket or purse.