The new water-based glues may appear to be expensive but when you consider they are much thinner than the older glue and how many more rubbers/blades you can glue, they turn out to be good value. For example, one 25ml tube of XIOM I-Bond can glue about 20 rubbers.

The STIGA Syncro BTG glue is highly recommended because unlike a lot of other water-based glues it is not difficult to remove the rubbers from the blade when you use Syncro.