For a business venture I would be very careful in costing the final print. For printing on "Fine Art" papers I would think that you should be able to match a good pro lab for cost and quality on an apples for apples comparison, since you are based in the US. Remember though that most labs producing inkjet prints on "Fine Art" papers will be doing so using pigment inks. I don't know what type of ink your current printer uses.
For straight "C-Type" colour photographic prints on glossy, luster, pearl/metallic papers then a good lab may well be quite a bit cheaper than you could create similar at home. This is one category where like for like comparisons are not possible. But even so in the US you can get some very good deals on paper and ink that will still make printing it yourself cost effective. Longevity of the print in this situation can almost be down to the exact circumstances of the final display location. Hang almost any print in direct sunlight and it will deteriorate quite quickly regardless of process type.
One situation where it may be worthwhile finding a good lab is specialist output. I love to work in black and white, and I have found nothing that looks quite as good as a traditional black and white print on silver halide paper. I have found a lab that prints digital to Ilford MG IV paper, in both RC (glossy and luster) as well as a FB option. These are not cheap prints, but a discerning buyer would most likely be willing to pay the price for the ultimate in black and white quality. So it is at least worth knowing that these options exist.
Here in the UK things are actually quite a bit simpler, generally you should be able to find a pro quality lab that can produce prints that will be at the most only as expensive as the consumables that you would use doing it yourself. Doing the prints at home you would still need to allow for the cost of your printer. So in general DIY printing is not commercially cost effective to any degree. I've pretty much stopped doing A4 (12×8) sized prints on my Pixma MG5150, they cost about £2.50 each in consumables. The lab I use charges only £1.15 for A3/16×12 prints, so that is now my standard size for a print for my personal use.