[nibbleshifter]

Simple solution: buy gold and store it.

100k$ of gold as 100g bars + their certificates of analysis/authenticity fits in a small lunch box. Bigger bars allow greater storage density, but are harder to offload.

The problem is you now are exposed to fluctuations in the gold market, and offloading gold in any sizeable amount is a pain in the arse.

[nerdponx]

Realistically, is it hard to sell a lunchbox worth of gold for its fair market value?

[tastyfreeze]

Depends on where you live. Generally, the answer is no. Gold is easy to move in pretty much any quantity. Local coin shops want gold they can move easily. In some areas that is gold in any form. In others sovereign coins are more popular than bars.