Why does it say the inventory is not available?

Steam only shares an inventory that is set to Public. The owner can change it under Steam - Edit Profile - Privacy Settings - Inventory. It can also mean the account holds no Rust skins.

How are the skins priced?

At the same canonical price the whole wiki uses: Steam's lowest sell order for the skin, or the highest buy order when nothing is listed. Skins with no Steam market listing show as unpriced and count as $0.

How fresh is the data?

A fresh read from Steam is kept for 24 hours; the Reload link forces a new read. Prices are always today's.

Is the Rust inventory value accurate?

It is what the inventory is worth on the Steam Community Market right now, which is what almost everyone means by inventory value. What you would actually receive in a sale is lower: Steam takes roughly a 15% fee on every market sale, and thinly traded skins can take a long time to sell at the listed price.

Do I need to log in or send a trade offer?

No. Everything is read from public Steam data, so there is no login, no API key and no trade URL - which is also why you can check anyone's inventory, not just your own. It is free with no cap.

Can I see what an inventory looked like before?

Yes. Every day an inventory is checked, a snapshot of its items and that day's prices is saved; pick a date on the result page to view it. The value chart also has longer ranges and a custom date range.

Can I use this from code?

Yes - the rust.wiki API exposes the same lookup at /api/v1/inventory/{steamid} with an API key.

Rust 库存价值计算器

粘贴 Steam 个人资料链接、自定义 URL 名称或 SteamID64，即可按本百科其他部分使用的同一套 Steam 实时价格，为该账号的 Rust 皮肤估值。库存必须在 Steam 上设为公开。免费，无需登录，无需交易报价。

指南： Steam 交易限制：为什么无法交易以及如何查询

已查询的库存

58,829

已查询的总价值

$18,892,530.14

最有价值的 Rust 库存

第 923 页，共 2942 页

#	玩家	物品	价值
18441	afacan	62	$135.45
18442	Trippled_gg	43	$135.45
18443	KoshiDance	41	$135.44
18444	Blue	67	$135.44
18445	EnemyDragon	92	$135.41
18446	Cheerio	106	$135.40
18447	DM Bot # 6930	26	$135.39
18448	kk	39	$135.36
18449	Dirig0	53	$135.36
18450	三PANDA三	58	$135.33
18451	123	31	$135.33
18452	Le Gamble	62	$135.33
18453	Droogs	97	$135.32
18454	5 BIG BOOMS ...	88	$135.30
18455	FERM	19	$135.29
18456	babo45	84	$135.28
18457	SoggyBoy69	63	$135.23
18458	Greeny	31	$135.22
18459	Exe^	114	$135.20
18460	bob-8	49	$135.19