Honestly, that sounds about right. I know some attorneys charge more than that...and some charge a little (not much) less. The filing fee alone is about $200-$250. As far as payment plans on concerned, that's going to be up to each attorney whether they will accept that kind of arrangement. Most I know won't do payment plans for ODLs (and neither would I).
The above is for academic purposes and is not intended as legal advice. The response does not constitute the creation of an attorney client relationship as this forum does not provide for a confidential communication.
As pointed out there are costs to file the case in court and with the DPS. In Denton County, the judge requires a hearing, which takes time-more than other counties. He is a fine judge and will be fair with you if you file and proceed alone. I - and probably some other attorneys - will prepare the documents for you to file. You can save some money, but it will be more difficult and risky than if you use an attorney. You can file your case in either the county of your DWI or your residence.
According to my colleagues in Texas who have already provided excellent responses, it looks like you've got some options. I strongly recommend using one of them to handle this, as your livelihood is at stake. Even if their fee is a stretch for you, it's worth it to get this right.
If this was your first offense and you completed the Texas Drivers Safety course timely as part of your probation your license should not have been suspended. I would contact the attorney who represented you in the DWI for more information on why your license was suspended.
In Denton you would be in front of Judge Ramirez. He is fair and $1000 is the usual rate because the filing fees are over $250.00 plus the legal fees to prepare the Petition and the judge REQUIRES a hearing.