In most writing classrooms as well as on most rejection slips, you'll get a suggestion from teachers and editors that you read a literary journal before submitting to it (or read any literary journal before submitting to another one) in order to get an idea of what they might like.
There are a few problems with this advice. 1)Time: Many working poets find they don't have the time to read EVERY journal they'd like to submit to. OR 2)Money: They might skim over them at the AWP bookfair, look into their wallets, and sigh. There just isn't enough money, or usually a well-enough stocked library nearby for poets (or writers) to read every journal they'd like to. $20 bucks a pop doesn't get you very far on what most people have to spend. I know my subscription/ conference registration/ contest entry fee money comes out of a small grant I was lucky to get and have just about used up :(
Which is why I've spent a little bit of time lately going over journals I've read in the past or recently submitted to, looking to see who has affordable back issues/ sample issues. Some back issues are rare and thus legitimately expensive. But if most journals are anything like Hayden's Ferry Review, there's a room somewhere full of back issues that the magazine can't afford to store anymore, would give away free if they could. Maybe the editor ordered about 200 more than needed from the printer, the cover art wasn't so great, the issue came out during the Arab Oil Embargo of '74 and people just weren't buying journals like predicted. Thus the sample issue, as in "I've got 200 copies of issue #20, pay for the shipping and it's yours." And some magazines just don't charge that much, period.
Here's a list of links to back issues pages of literary journals that sell for less than $10 a piece. Although some of these might still be more than half of a current subscription (and some aren't), it's enough to get a taste of what the magazine's about and then decide which ones you want to add to your Christmas list.
Hayden's Ferry Review $7.50
American Poetry Review $4.25
Copper Nickel (issue 5) $8
Crab Creek Review $6
Cream City Review $7
Gulf Coast $8
I suggest issue 20.2 featuring my dear friend and Pushcart nominated writer, Aimee Baker.
Mid-American Review $5
New England Review $6
New York Quarterly $8
Slipstream (some issues $7)
Cimarron Review (some issues $5)
The Gettysburg Review $6
There might be more! Check out your favorite lit mag, and if it's got a good sample issue rate, let me know.