The salon markup on nails is mostly labor and chair time, not product. Once you own the powders, gels, and a lamp, each manicure costs only a few dollars in consumables - which is why doing your own nails is the cheapest long-term option by a wide margin.
What a kit actually costs
A starter kit averages about $60: a dip powder set, or a gel system bundled with an LED lamp. After that, at-home dip works out to roughly $2 per manicure and at-home gel to about $3 (dipwell.co), since you are only replacing powder, base and top coats, and the occasional file.
Year-one math
Do your nails every three weeks and that is about 17 manicures a year. Year one is roughly the $60 kit plus $51 in consumables - around $112 total, including the equipment you keep. Every year after that is closer to $50. Compare that to $500–$1,900 at the salon and the kit pays for itself after about two visits.
The honest trade-off
The savings are real, but a clean at-home application takes practice, and removal still needs patience to protect your natural nails. If you refresh on a steady schedule and do not mind a learning curve, the at-home route is hard to beat on cost. Use the calculator to compare your salon spend with a DIY year.