Welcome to the hobby bro, hope you stay on with it for a long time. I've nvr bought from AA website but the price there is their RRP, which is usually more xpnsive than other online sellers. Plus shipping cost it will set you back a few bob more overall. So in my opinion buy elsewhere such as from ebay or other online stores. I can get you Lambos as well, have a look here [WTS] Autoart/Minichamps/HW/Norev Diecasts

Regarding brands, blu3hamm3r already xplained the lot. Then again, it all boils down to your budget.
Happy hunting...

The selling price at AA website a bit higher compare with our local diecast seller----> diecast empire. I suggest u better buy with him as his price is cheaper and can be ship out faster than u buy from AA web page.

For Lamborghini, it depend on what model u r looking for. MR only produce resin model but not diecast. The Lamborghini is fully sealed. If you dont like opening part on ur model, then u can consider MR or Frontiart. Both of the brand producing resin Lamborghini model. MR price will be higher bcos all model come with limited unit only,  Frontiart can consider a fresh brand which producing resin model on Lamborghini, the price a bit lower compare to MR but the quality wise can said pair with MR.

For diecast, there are few brand making Lamborghini model. AutoArt, Kyosho, Norev, Bburago, Maisto, Mondo Motor. Mondo Motor, Bburago and Maisto produce low end diecast of Lamborghini. The quality is low, the paint job so so only, the finishing is suck. Price range around RM50-200.

As for AutoArt, the Lamborghini come with more detail, finer finishing and better paint work. It produce 1:12, 1:18, 1:24, 1:43 scale. Price arange is around RM380-480.

HW Elite also produce some Lamborghini model but only at 1:43 scale and limited model only.

As for Kyosho, it produce a lot of old Lamborghini model such as Lamborghini Jota, Jota SVT, Muira, Muira SV, Urraco, Countach...... Althought AA also produce Muira and countach, but Kyosho Lamborghini come with better detail and more opening part compare to AA. Price arange around RM290-340. See the below:

The Miura models by Kyosho have the following details that AA doesn't have:

-Antenna
-Side mirrors
-Opening fuel filler cover
-Seatbelts

Although the AA Miura is good too, but Kyosho have more variants

-P400
-P400S
-P400 SV - the best Miura varaint in my opinion
-Jota SVR

and soon to be added, the SVJ. AUTOart only has the SV.

Kyosho also have more variant of the Countach models

-LP400 concept
-LP400 production car (Blue, red, white, black, orange & yellow)
-LP500 or 5000s (white, red, black and yellow)
-LP500S (blue & red)
-LP500R (black)

For new Lamborghini model such like Gallador, Murceilago, Diablo, Reventon, LP-560,LP-550,LP670, so far AA have better quality build compare to other. Fyi, Norev also produce LP-670 SV but only limited color available. Hope this help u.