Ok, I'll try to help a bit. But I don't use a dongle, I use an Ipod, so I have no knowledge of the differences in dongles. But if you have an Ipod, many will work, also many modern cell phones will work. If you are on 3.50, then you need to make sure you pick a device which can downgrade as well as JB. Ipods can, I think androids can, most devices can. If you updated your PS3 this week, then it is on 3.55, and you are out of luck. If you don't have a device already capable like an Ipod, perhaps someone else can point you in the right direction. Rockbox-PSGroove is what you need for Ipods. See here, it tells you all the Ipods that work, and there is an installer program if you are not tefch friendly.
Downloads | RockBox-PSGroove Installer
Here is a list of phones and other devices that will work, but I don't know if its up to date.
Device compatibility list - PSFreedom Wiki
A few Texas Instruments calculators work as well.
However, WARNING, you may disable blurays and movie playback.