IS SELF-EDITING A GOOD IDEA?

Should I self- edit my own manuscript? I did consider a professional editor, but I don't have R20 000 for that.

I did some research on the Internet, but I didn't get the answers I was looking for. I just don't know if I am objective enough to pick up any writing mistakes. I can check for grammar and spelling errors, but what about the technical stuff? I read an article where the writer said that if there are any mistakes in your novel, it will get rejected immediately. If you want your work published or if you want an agent to take you seriously, your manuscript has to be polished and in pristine condition.