Your model is quite large! It's certainly a good thing that you've allowed for drain holes, to keep costs down. It might be practical to not reject other methods of printing. I have a couple parts that have been created using SLS, a laser sintering system that effectively melts fine grains of nylon powder. The surface is completely layer free and has a very fine grain texture. A single coat of primer would flatten that texture easily. It may also be less expensive than SLA or other resin printing technologies. I see that the service provides for a much larger build capacity in that method, allowing for a single piece, although I don't think that's a show-stopper or a major factor.

Have you also considered that some filament types will perform well with post processing? PolySmooth uses vaporized alcohol to remove layer lines, while ABS can be easily smoothed with vaporized acetone. I've done just that with wonderful results. If you want to create a small test model, I'd be happy to build a print in ABS, vapor-smooth it and send it to you for shipping and material costs only. There is some dimensional loss with vapor smoothing but it appears that your model is not a technical item as much as an artistic one, yes?