The mount that you have shown is just a car mount, it does not charge your PDA, it does not have a in-built speaker. For such a basic mount, IMHO $35 is a little bit on the higher side.
Arkon and Seidio are two good mount makers. You can get a list of all their mounting configuration from either
buygpsnow.com or
semsons.com. They have various combination of mounts...mounts that just hold the Axim, mounts that will hold your Axim and charge it too, mounts that will hold your Axim, charge it and also has an in-built speaker with the mount so that the Axim's audio can be outputted to this speaker for listening to MP3 songs, GPS audio instructions, etc.
Some time back, I remember seeing this % or $ discount code floating around to be used for buying one of these mounts.
Just FYI for powered mounts, if you did not know it, Arkon mounts are not PDA specific, so if you buy an Arkon mount it will work for your Axim X50 today and later if you buy some other PDA it will work for that too (provided you buy the cable). Seidio mounts are PDA specific, so a Seidio mount for Axim X50 will not work with other PDAs. But then with Arkon mount, once you put your Axim on the mount you have to then connect a cable. With Seidio mount, you just put your Axim in the mount and you are all set to go. Seidio mount are no doubt more convenient than Arkon mount.