Hey - seeking some advice re best options for data for a tablet.

I'm currently on just a $19 pre-paid monthly pack from 2 Degrees; I'm planning on shifting to the $29 carry-over plan, given the 500MB is more than enough for my mobile so I should just about cope with this spread over a mobile and tablet using 2 Degrees data-sharing. (The ability to carry over data  is a key advantage to these 2 Degrees plans).

That said, assuming that a total of 500MB between devices is adequate, are there any other good-value options from any of the NZ providers that I should be considering? I've loooked at their websites and can't find anything that stands out, but thought I should check. Eg, 500MB for $15 (Telecom) or $20 (Vodafone) isn't really worth it, given it's an additional $10 for moving to the 2 Degrees carry-over plan which will enable me to share the data. I can't see any data-only plans from Skinny.

My new phone's a 4G model, as will the tablet we purchase, but at this point in time having 4G data speeds isn't a must-have.

Any advice much appreciated!