From “Ask Kit!”:
Q: What can I expect to pay for providing soap/lotions/shampoos/per room?
A: You can go hog wild on that and spend as much as $10/room. Don’t. Since you are providing a more simple experience I think your amenities can also be simple. You should be able to get by with $1-2/room, especially if you use refillable dispensers for soap, lotion, shampoo, and conditioners. Do have a small bar of soap too — some folk need that. From both a cost and environmental perspective, bulk dispensers make more sense than individual packaging.
If you ever become a luxury experience, that’s a time to consider expanding your toiletry options, but still be careful to not go hog wild. I enjoyed a presentation years ago at a B&B conference where the speaker had a table loaded with wonderful toiletries. He acted as if that’s what his luxury hotel offered guests. After talking about them briefly, he dramatically swept them onto the floor, leaving only soap and shampoo on the table. Then he proceeded to talk about how much is reasonable and what guests really want and expect. Each property has its unique answer to that question, but be aware that you can unnecessarily go too far with toiletries.