Thomas, I hope you do get a Mat, or something similar. TLRs are great fun to use, and the Mat is capable of great results.
If you do get a 124G (or a 124?), be aware of one quirk. They have a selection switch for X or M flash sync. If you use the self-timer with that switch set to M, it jams the shutter............ I think. I know it's something bad. Many people use a small screw, or glue, to lock the switch to the X setting.