The Ruger P Series can be found for under $500. Rock solid reliability. The Ruger SR9 can also be had for around $400 but has had some early issues. Taurus makes several that would fit the bill. If you search you may be able to find a S&W M&P for under five hundred.
Are you opposed to buying a used weapon? Because if you are not it will open up a ton of choices.
Bud's had a Sig 2022 for $479 the other day.