$29.99 is for ONE state
you cannot add another state for another $29.99
$99.99 is for all states they cover, and the only way to bump up from a single state.
If you upgrade from the same source you used to purchase the single state, it will pro rate the single state cost and deduct the remainder from the $99.99 fee.
The "nationwide" layers will show for all states even though you only purchased one state.
You can "add" other states, up to 5 total, even though you only purchased one. Adding those states will enable the game unit boundaries. You will then have 4 addl states with sat/topo/hybrid layers, roads, and national layers, available for Internet Scouting on the OnX webmap. You can download the sat/topo for offline use, and the tracking feature will work in those addl states.
You cannot download the addl "paid for" content (BLM/travel mgmt. areas/Migration/etc) for those addl states.