As far as creating a potion vendor yes. You could find a potion #fi potion of
Find the item ID.
#findspell nameofbuff
Go to HEIDISQL or whatever you use to edit your database. Go to items (data tab). (Likely need to Show all).
It is probably already sorted by ITEM ID. Go to the item ID you searched for.
Right click, duplicate row. (I do not think auto increment is on in items so find an ID that isn't used 400,000 or something). Or whatever unused number you want (remember it though).
Probably at the very least want to change the name of the item. And you want to put the spell id under Click effect.
Look up on google eq emu items. See what each column does.
http://wiki.eqemulator.org/p?Items
You may want to set restrictions (cast time, recast time, price, etc) If you want to make the potions have more charges or infinite charges change maxcharges.
Then use this guide to create a merchant NPC:
http://www.eqemulator.org/forums/showthread.php?t=33005
(You add the items to the vendor (with the merchant id you assign) under merchantlist.
Which requires- Merchant ID, Slot which you can start with 1, item ID (you created), faction required if you want to change, level required if you want to change, alt currency, classes required (65,535), probability 100.
I have never added a buff bot, but there are a few examples, do not know if they work or not:
http://www.eqemulator.org/forums/showthread.php?t=23168
http://www.eqemulator.org/forums/showthread.php?t=29401