I ask again;- why can you not use the fuse as a shunt? It might not be as thermally stabe as a custom shunt but if it's there anyway, there's no extra cost involved.
I have just bought one of these Powergauge - new from Merlin, it seemed a good compromise on price / features and will fit into a spare 52mm gauge hole in my dash panel. Fitting it this weekend so we'll see how it goes.