I can't be bothered to try without epics - because, really, how many medium and bigger guilds cannot get them?
Honest question: what size do you consider Ikoko Knights, with our 76 members? We've got 2 Inferno Hammers, 2 Air Javelins, and that's it, and we can't get any more due to lack of funding. We're making ends meet, but we have plateaued and haven't grown in a long while.
Seeing that majority of those members are below 100 and about 40% of guild XP is retired members, I'd say that you will be medium soon

- but I thikn that if the few higher-level members started working a little for the guild, you shouldn't have a problem putting funds together for a level 300 epic quite easily.
I remember when I was about level 130 how we spent some serious fund-raising efforts as a guild to get together a bunch of forged gear that, while not a set, still was a profitable way to 1hitkill 130-140... We introduced a policy that anybody on level 130 had to contribute 1FSP per each level they made till about 170. Later, as FSP price rose, we shifted this one-time-payment duty to higher levels and finally abolished it together - and there's just a gold tax now, stretching from peanuts at low levels up to 200k per level at some 800+ or so.
It's not easy at lower levels, but if you get all people to actively cooperate, if you convince them that those spending money will be able to make good decisions and spend for everyone's good, it is doable - and for that team work, the guild is then rewarded greatly.
BTW, earth hammer for level 300 would right now 1 FSP per guild member excluding the inactives. Is that a big problem?
And another "BTW" is money-wasting. What's your total guild upkeep? Ours is <80k.