There are many things which are related to budget you should assign on adwords. There are many companies who spend less on adwords. While some invest huge amount on paid advertising.There are many factors which are related to adwords budget which are as follows-

1- Traffic from other sources.
2- Sales goals of the company.
3- Revenue generating company through adwords.

It is common question among every one that how much budget you should assign for adword. Paid advertising is an effective medium to generate sales leads. You can get qualified sales leads through paid advertisements. Although you should target audience and prepare conversion friendly landing page.