Sorry that it is the first point. Can you price love ? We, as lovers, know that money has nothing to do with the love we want to express. However, tradition (and some jewelry stores) defines the budget for an engagement ring as two month of salary.
This statement should not be the rule, for the simple reason just said earlier. If you buy a $10,000 ring and you earn $5,000 a month, that's tradition (and a big diamond). If you buy the same ring while earning $50,000 a month, then hope she doesn't know the tradition.
That was just an example, the price will of course be determined by the diamond quality and size and the ring metal but your salary should not influence the price of the engagement ring. You will certainly find the perfect ring for less than that online, the next steps will tell you more.
Remember that to build your own engagement ring means to create something completely unique, a symbol of your love, not something you want to value.
Setting a budget will be very important for the choice of the engagement ring. You have also to know that if you know what she wants, what she likes, the price of the jewel will not be a determining factor in her decision to say "yes".
Next step, few things to know.
The steps to create your own engagement ring :
Establish your budget