You get what you pay for up to a point. King stone 1000/6000 grit is the cheapest and a lot of people start there as entry level to japanese water stones. It dishes very fast and cuts slow on stainless.
I like shapton pro. Not too expensive, box doubles as the stone holder, splash and go, doesn't dish too fast, and moves metal quick. Splash water on, start sharpening, let it dry indoors not in sunlight. It's the same as shapton pro - but the japanese market version is a little cheaper.
If by inexpensive you mean like wusthof pro or victorinox type stainless steel then stop at 1500 or 2000 grit. If you have vintage carbon steel you can add one more stone for finishing 5000 or 6000 grit. For repairs 320 grit, but you can also use your existing coarse stones for repair already i think.
In conclusion- you only need the 1500 grit one i linked for stainless