I have an assault with bodily injury arrest in Bexar County (Texas). I was arrested, posted bond, I went to court and the charges were dismissed. How long will this stay on my record and how can I get it expunged myself without having to pay a lawyer a ton of money?

There is no record to explunge, if your charges were dismissed, then there is no conviction record.

It will not show up on your official police record. The actual arrest may show up on some private background searches but only as an arrest.

There is no way to explunge a "arrest" since first it does not effect private background searches

Well I got denied a job because of it. We are going to be renting an apartment if they do a background check will it show up?

They must have ran a private, but again, arrested means nothing, 1000's of people are arrested and found not guility or dismissed. Did they know you were dismissed ?

You could get a certified copy of the Final Disposition in your case from the Clerk of Court showing that the charges were dismissed. The Judge has to sign off on your case to make it legal. A certified copy (one with the Clerk of Court's embossed stamp on it) will cost you about $1 for plus postage and copying fee of 25 cents will work wonders for you in the future should something like that job denial you had.

Background checks for apartments will only be looking for convictions, not arrests.