It's hard to get the exact value of the deck, but pretty much everything besides duals, fetches and forces is like 5$ max, sometimes even only a few cents.
I'm European so I have access to magiccardmarket.eu which is like the best place to buy cards from private people and way cheaper than buying them from official sites (I don't know about the American equivalents, but I'm sure somebody can help out). When buying from private vendors I like to look at their total collection of cards they own, if it's like only nm rare cards and they don't have a lot of sells I'd shy away since both signal me that this guy might sell chinese counterfeits. Getting a jeweler's lupe for like 5-10 bucks can also help immensly identifying those, but is only required when buying from private vendors.
So here're the prices (in €). I won't care about the language, but keep in mind that cards that are too damaged aren't allowed in tournament play.
3x Volcanic Island (revised) ~ 540€
2x Underground Sea (revised) ~ 550€
1x Tropical Island (revised) ~120€
note that duals have spiked because everybody panicked about a lot of new players in legacy with eternal masters and the finite amount of duals that will never be reprinted, personally I'm not too sure people want to get into a format just because they happen to open a Force of Will. I predict them going down a bit once the initial panic has settled.
Force of Will (alliances) ~ 200€
It's already going down, but shouldn't really go below 40 imo, it's not a bottleneck card though like Tarmogoyf was in Modern, so the reprint should free up some supply (I e.g. want to sell my old ones for some new art).
4x Polluted Delta (Khans) ~ 68€
4x Flooded Strand (Khans) ~ 60€
Fetches are currently going down because they're dropping out of standard, so it's a good investment to pick them up in the next months, they'll certainly rise again a bit since Modern and Legacy have a demand for them.
Other stuff ~100 € (estimate)
Please note that this doesn't include shipping costs, this might be up to 5€ per shipment. So you should look at spending approx 1800€ with the current prices, but as I said it's a bad times to pick up duals, given they're dropping you might be able to save a couple hundred bucks if you pick them up later.
This is a high price and a reason why you should try to build up your deck slowly, make deals and trade for cards whenever possible. This can save you a lof of money compared to when you want the deck immediately and just buy all the cards at once from an official vendor (the deck might be well over 2k from them).
Personally I built my deck slowly over the last 2 years and am still missing a Volcanic, I have a friend though who lends me his when we go to a tournament and might eventually sell it to me. I found that most Legacy communities are very generous about lending out cards, they all know it's a high cost barrier to enter the format and everybody wants people to play with.
If I was you I'd get all the small stuff and as much big stuff as possible for as cheap as possible and try to borrow the rest for the time being.
To the deck itself: The reason why I like this deck is that you have chances against pretty much every matchup, even lands (though it might be only 30% if your sideboard is bad. The new card invasive surgery will propably help a lot though). It highly depends on your knowledge of the deck and matchup as well as your sideboard plans. I always find it funny how much people discuss about maindecks, but not sideboards even though you play most of your matches against every deck sideboarded.

