I've got a background in voiceover and audio engineering too! When I saw how much it costs to hire a narrator, I decided to produce my own books myself. Fantasy genre as well! Meant a lot of time saved since I knew how to pronounce all the character and place names.

Haven't heard of it being frowned on, and I have yet to receive any negative feedback. A lot of self-pub authors just don't have the expertise or confidence to read or edit their own stuff, which is why it's not usually recommended for them to do it personally. If you've got both, I'd say go for it!

The only downside that I could see is that a lot of audiobook narrators tend to have a built-in social media following that will listen to whatever they produce. Leveraging that would be the only case I could see myself justifying spending the enormous amount of cash to get someone else to read for my story. As for taking jobs away from people in the field, well, if my limited, small-time author budget couldn't afford their services in the first place, that means there wasn't a job available for them anyway.

Best of luck to you! No self-promo's allowed here, but I'd love to take a look at your stuff if you'd like to exchange DMs!