Alternative to vending machines?

Vending machines haven't reached Sri Lanka because of what? Just haven't caught on? Too expensive for locals? Power issues? I'm sure in a country like Sri Lanka, you have cigarette vending machines - they could always work for small items.

Without knowing the layout of your reception, it would be difficult to give you a helpful answer, but:

You can always get a tall glass fridge that sits next to the reception desk with the prices on the fridge, and the guest just helps themselves to whatever. Or you can get a small fridge that sits on the receptiontop (like a Red Bull fridge) and again the guests just help themselves.

That would drastically reduce the time involved with interuption. If your receptionist is busy when someone comes to get a drink/snack from the new fridge positions, the guest can always just leave you the exact money on the top, or gives you more money, and you just give them their change back later. Sometimes if the bar is busy, and the guest wants a towel/soap, etc, and they don't have the exact change I just say sort me out later and 95-99% of the time they come back in an hour, or pay the next day.

Robert

Vending machines are nice and convenient but not a biggie if you don't have them. I think most places rather than going for the initial outlay of the machines and their maintenance prefer to enter into a contract where they get 50% of the profits and the third party company provide the machines, the upkeep and the goods.
Personally I think there's a lot to be said about the personal approach of the 'little shop' with the only drawback of it only being available outside office hours. The shop I have at my current hostel is a good model for anyone wanting to start one on a very small budget.
Start withe the basics. I put in a £50 budget. I went and got shampoo, shower gel, toothpaste, toothbrushes and that sort of thing. When we sold out we replaced them from the local pound store. After about a month I had a total of £50 in stock and £80 in profit (I run a 32 bed hostel). Over the next few months I just used the profits to expand the range. We now have a range of drinks and foods. Basically anything that we think will sell. Getting postcards of the hostel made up is a really good seller but I have to say the runaway winner is travel adapters. We get through tons of them and make a 200% profit on them. I took the place over about six months ago and we're not comfortably taking £40 a week, not a huge amount but that's the same as 2-3 beds and almost £500 a year.