Looks like I'll be driving through, but still spaces on Central branch bus for around £11 pp.
Had a look at trains earlier and it's possible to get there for £13.10 return from Glasgow if pre-booked , but not easy as cheap trains are at shit times.
Outward....
Virgin train
d Glasgow 1109
A Carlisle 1225
then Carlisle to Annan Sscotrail train 20 min journey eg d 1312, a 1331
Return
take time leaving Annan as cheap Carlisle to Glasgow train is
d Carlisle 1911
a Galsgow 2034