A few months back Spark added data stack to their prepaid plans for those using the Spark app. For each month you are a customer on prepaid they will add 100Mb extra to your plan.
I've just seen that for the next 3 months they are actually tripling the offer, so at the end of month 1 a 1.25gb plan will boost up to 1.55gb, by February this could be up to 2.05gb a month.
Not a deal as good as some workarounds on other networks but worth knowing for those considering moving or already on spark if they didn't know. Seems you can also add the socialiser in this deal to prepaid to help out for the first 6 months while you build up the gigs.