Full Tutorial (with possibly all equipment/weapons):
I haven't checked to see if it works, but as Decency said in his post simply make a buy script. What this does is allow you to bind keys to buying weapons.
First to make a script just use a text document and save it autoexec.cfg in Steam\steamapps\common\Counter-Strike Global Offensive\csgo
Next you fill it in with things you'd want to buy. Taking the script pointed out above, you could say:
//Print to console
echo "Press F1 for AK-47 / M4A1"
//Set items you want to buy, seperated by semicolon
//Alias sets the following word to a variable to be later used
alias buy_ak-m4 "buy ak47; buy m4a1"
//Then you bind it to a key using the alias!
bind F1 "buy_ak-m4"
What I also noticed is that there is an autobuy script already in csgo, that you can type autobuy into console and it will work. You could try modifying that script to fit your needs.