it's nice to have the personalized soaps and things if you can afford them. i could not. i remember seeing a guest at a place i stayed at loading up on soaps and shampoos that were in a basket in the hallway. she said 'they are here for the taking' i say that was just plain greedy!
for lower budgets like mine ... i put a stamped logo on sheets from a ream of stationery paper i bought
vistaprint postcards (nice harbor pictures) with compliments of and the name and the address of my place. i put a few postcards in each guestroom ... (guests loved those)
one thing i did splurge on was chocolate covered (dried) blueberries in tiny bags i did up with my own cards saying compliments of, enjoy your stay ... in the rooms. guests LOVED them (even if they didn't love the berries, i think they liked the personal gifty thing). there is a wildly popular inn up near where i was that put a small tray of chocolate kisses in the rooms, so sometimes i did that. looked great, cost little and was well received.
carol of thurston house puts a big chocolate bar and a welcome card on the pillow of the guest rooms. i loved that, too!
i guess i'm not really answering your question about a budget amount for guest give-away's, am i? what my guests seemed to appreciate most (and what i as a guest appreciate) are the snack items in a guest room or a guest area ... info and little guides or maps with the inside scoop on best places to go, places not to miss, schedules and the weather ... free wifi ... little touches. knowing that if i forgot my toothbrush, i could get one from the innkeeper. as an innkeeper, i wasn't asked for these items often but when i could just say 'here you go' the guest walked away beaming and i felt pretty good.
just be sure, if you give away pens, to TEST them and make sure they are worth giving away. i mentioned a while back about boxes of pens that have dried up or pens that leak or break. not a good item to have your name on!
if you're giving it away to promote your place, make sure it's stuff worth having.