Too bad you aren't near me otherwise i'd recommend possibly the best RC shop in australia.
It is mostly the layout. The M05 is loved by all who use it. A favourite among mini racers. Personally i think it handles just like the real thing. Weight distribution is spot on. The M03 is the predecessor and is as it would happen, worse. There are some who prefer the M03 because of the higher centre of gravity and feel of the car. I'm no expert but i race with them from time to time and this is their opinions and being so, they vary. I personally prefer the M05.
I would suggest talking to someone at an RC store who does know about these a bit better.
Depending on whether you want to go to a shop or get it online, the prices vary from about $130 to maybe $250, RTR or kit. There are aluminium kits, I wouldnt recommend it as if you want to take it racing, some carbon fibre parts are more ideal. I would give yourself a $300 budget for a decent base. You mentioned you wanted to build it yourself, great idea it really does help.
I would recommend servos made by Savox or Hitec, they are very trustworthy and make some all the way up to 1/5 scale however you won't need anything near that big. too much torque in the servo and you could snap the steering completely.
If you want to just get a good quality cheap radio, FlySky are a good bet. Their GT2 or GT3 are great examples. If you want to get one that is a very good quality, best of the best, i'd recommend a Spektrum or Futaba. That would be pushing it though as you can spend up to $400 on the radio alone. Depending on whether or not you want to put lights on it or not you will need a 3 channel radio. If not 2 channel will do fine.
I presume you will want to upgrade it slightly as well so i would recommend a full ball bearing kit as it comes with plastic bushings and they are terrible. Another is the shocks and springs. The standard ones are friction shocks and are extremely flimsy. I once flipped my mini and the shock completely disintegrated. You just push them together and they come apart just as easily. You will want some oil shocks and preferably threaded for ease of adjustment.
The next upgrade is the Steering arm. The standard one is a high load bearing area and under race conditions can break easily. I would recommend upgrading to an alloy one such as this one:
http://www.ebay.com.au/itm/Tamiya-Mini- ... a32&_uhb=1If there is money left in the budget then you could look into a brushless motor and ESC. An alloy motor plate would be useful also. Then there is the choice of what type of battery to run. Either NiMh or LiPo. NiMh are the standard ones but LiPo provide a more efficient flow of power and can produce alot more of it. They also hold their charge longer but there is a downside. You can run the risk of them overheating and actually catching fire. However, to run LiPo you need an ESC and all decent ESCs capable of running LiPo have a charge meter and heat detector built in. an Automatic power cut off to stop them from discharging to a level too low for them to be recovered. Then you can get a decent charger to charge those batteries. then tires aswell.
If you want to skip looking for all this, This should cover most of the necessary upgrades:
http://www.ebay.com.au/itm/Blue-alloy-c ... cd7&_uhb=1Hope this helps! Just depends on what your budget is. You can buy a kit for as low as $100 but you can spend $1000s on upgrades.