There isn't really a minimum and I don’t think the cost side of it is really a factor when considering a donor advised fund. The charge is similar to most investment managers, so a sliding scale of a certain percentage of assets under management, which obviously lowers the more there is.
To give you an example, our minimum balance on this sort of DAF that we're talking about is £25,000 pounds and the minimum fee is a few hundred pounds when you're at that kind of entry level. You wouldn't set up a donor advised fund with five thousand pounds but once you're into the low tens of thousands you become eligible to open a donor advised fund and I think that cost is not really a factor.
Likewise at the top end we have some DAFs that are the best part of a hundred million pounds and people think “oh surely once you're at that level you need your own foundation”. It's much more to do with how involved your client wants to be in the day-to-day admin of giving and how directly accountable and liable you want to be for that activity – that's what I tend to say to people at both ends of the scale.