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

58,644

已查询的总价值

$18,871,814.12

最有价值的 Rust 库存

第 211 页，共 2933 页

#	玩家	物品	价值
4201	Meat-Sword	667	$986.31
4202	Maxr	166	$985.87
4203	SouL...	569	$985.75
4204	Gandhi	424	$985.74
4205	♛Limpan♛☭	234	$985.20
4206	Кексики	271	$985.16
4207	toxicplays048	685	$984.77
4208	S0las0^T.R.U.M.P.	408	$984.31
4209	Damage	311	$984.12
4210	Task King	261	$983.94
4211	carl	133	$983.78
4212	Fat Dabs	276	$983.67
4213	Insanes	94	$983.58
4214	Jurn	195	$983.57
4215	Chloe	228	$983.49
4216	123	61	$983.21
4217	Fall Aut Boy	568	$983.06
4218	Super	503	$982.96
4219	Beckyy	311	$982.91
4220	[TE]DR33D	285	$982.89