Here in Colorado the process is sealing of records. You need to notify the prosecutor/DA, the Court, the police agency that arrested you, the agency that held you in jail, and CBI. The process is not over time consuming. However, you need to make sure that you send all of the notices out accurately. If you miss one of the agencies, then it might be all for naught. The DA has the opportunity to object. Normally, they do not. If they do, they have to show why the public interest in knowing about the dismissed charge overrides your privacy interest in getting the records sealed. I know that you have referenced expunged. However, CO does not use that language (as other states do) and sealing is the proper terminology and the proper method of accomplishing what you are seeking. I have seen attorneys charge flat fees in the range of $500-$1,000 typically. However, every attorney sets their own fee and there is no standard fee out there. It is relatively rudimentary though and I used to sign off on them weekly with no objection from the DA when I was a judge.
You should contact several attorneys and check out if they really have done Sealings.
Expungement is for juvenile adjudications while sealing is for adult convictions.
All the Best
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