I need a mini laptop and a dongle I assume for on the road internet in my car so I can have 24/7 uninterupted access to 'ozbargain' among other things
what is the best/cheapest netbook I should get
what is the best/cheapest dongle I should get
what is the best/cheapest sim card I should get
'best' network is almost always Telstra. Depending on where you are, optus network can be just as good and cheaper (most ISPs resel optus). If you are moving around a lot Vodafone probably isn't a good idea.
You can either get a USB modem, a wifi modem or just use your phone. Whatever you do make sure it supports UMTS 850 and LTE 1800 for telstra or UMTS 900/2100 and LTE 1800 for optus. You can save money by dropping LTE if you need to.
Netbooks come in all types and depends on want you want/need.