Vicki says, "I am looking to be able to store my herbs for a couple years or so."
While I don't know that this method will make your stuff last several years ^^^ it may help with whatever method of sealing 'for posterity' you choose.
Oxidation seems to be the biggest 'bug' in storing almost anything. Sure there are other factors, UV, Heat, real bugs etc... but vacuum sealing (haha) seems to be about removing as much 'air' from the package as possible. Limiting the O2 available for degredation.
Get rid of the oxygen first and then seal in your preferred method.
Two substances come to mind and are fairly readily available.
Nitrogen and Carbon Dioxide.
I'll deal with CO2 :
CO2 is safe to handle if you use your head. Look up or ask about handling dry ice before you hurt yourself. It's like a hammer, a useful tool, but capable of injuring you if you use it wrongly. Wear protection. 'nugh said !
So CO2 is heavier than air. CO2 is stable (in a normal sense). CO2 is not a poison, but don't try surviving on 100% CO2, again read the cautions... again 'nugh said...
Dry Ice is readily available. Letting the dry ice sublimate to gaseous CO2 will displace air from the bottom up in a container. A clean sink with a cardboard bottom (to catch any shake from going down the drain. Go ahead and tape off the drain hole, the P trap will stop the CO2 from escaping down the drain, but no sense loosing a speck.
So you have some sort of tub and dry ice and stuff. The dry ice will take some time to go away, don't hurry, even
stir your stuff around in the sink of CO2 to ventilate it and get rid of remaining 'air'... A pound or two of dry ice would supply a sink with CO2 for a half hour or more of steady CO2 (depending on conditions... Oh, cardboard is an insulator and most sinks are heat sinks (conductor) , not good insulators so . . .
So, you have displaced the 'air' in your stuff and the intended receptacle... proceed . . . how much extra time will you get? Who knows... but if it was worth saving it was worth an extra couple bucks and a little extra effort.
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Colder stuff last longer. Just don't take it in and out of the reefer or freezer without letting it come to room temperature before opening. Any good cameraman or musician knows you don't open the case till everything is at room temperature or you will get condensation. Long term storage should go into the deep freezer, not your refrigerator's freezer if you have the option. deep freezers stay colder.