To be honest you will probably get something second hand that would be pretty sweet for $150.
The router i got would be perfect its reliable as, but would be an absolute nightmare to set up unless you were a networking wizz so i wouldn't recommend it, but it is below $150.
I rekon you will easily find someone getting rid of an HG659B which has been on sparks network off trademe and will probably be in that price range.
Alternatively I saw a fritz box on the "offers and wanted section" which would be sufficent. You will need a 73xx or a 74xx. Maybe your current router is heating up and overheating, do you have it locked away in a cupboard? That router is probably fine for a 100/20 ufb connection. It shouldnt be rebooting.
EDIT: Spark sell the HG659b for $199 inc gst + a $15 delivery fee so $214 all up inc GST. http://www.spark.co.nz/shop/internet/modems/spark-hg659b/ and it will be perfectly fine for connections up to and and beyond 200/200 for a home user. And they will support it if you have issues.
