Irok, who ever told you that SD cards are no longer being made and then told you about SDSC, SDHC, SDXC, and SDIO (I assume those are the letters you intended to tell us) clearly has no clue of what they're talking about since they just gave you the names of types of Secure Digital cards that are in fact still being made in mass quantities (with new capacities being introduced not even a year ago) while telling you they're not being made. I really hate store people for their advice without education sales practices.
In my research when I bought my camera years ago (back in 2005 I believe), the 2GB SDHD card was the highest capacity available with rumors of a 3 or 4 GB card arriving around the holidays, these days you can get the newest card with a 2TB capacity. Here's the deal. Back when I bought my camera, the assumed max capacity these cards were going to reach was 32GB as per the SD 2.0 specs. The hardware was designed around that. Should I need a new card, I should buy a SDSC or SDHC card with a capacity of 32GB or less since that was the assumed max storage capacity if I want to avoid most potential issues, though the camera might still work just fine with a card of greater capacity.
The only issue I would have is with the XC cards as they come with a pre formatted file system which gives the card it's capacity rating. This issue is eliminated by the fact that my camera can delete the formatting and reformat the card to a usable file system as can pretty much any computer used today. So really, it's not an issue, though whatever capacity I buy, I will get less out of it with the filesystem that I use as it's a less compressed format then what the XC comes with.
I assume the person you were told about that had trouble getting the card to work, bought a card off the shelf not knowing anything about it other then it's storage capacity, or was up sold a more costly card with too high a capacity (they were probably told "look 128 gigs of space, that's a lot of pictures and super fast data speeds so your pictures will save faster" "Okay, I'll trust you sales lady, I'll get that" 
), or they were unaware that they possibly had to reformat the card if they got the XC variety, or did reformat it and noticed they were only getting half the capacity or so not knowing that the rating was based on the preinstalled format, not actual capacity and complained about that. Best advice I can give you, look up the specs for your camera. If it says SDHC card, you're good to go with pretty much most cards, if it says SDSC (the original format) you'll probably have to look around for one of those cards (and not at any kind of a retail store that only carries the latest in electronics as they would not be carrying a card format that's been around since '99).
You can get 2GB SDSC cards online for $6... 4GB HC cards for $13... Just go to google shopping and type in the name of the card you currently have. You'll get options, I can promise you that much.
Ryat, still holding out on Star Citizen, read this:
https://forums.robertsspaceindustries.com/discussion/35149/atomiku-s-super-star-citizen-giveaway/p1
A nice person is giving away a free pledge package. Can't hurt to sign up for the raffle. If you win, you win, if not, oh well. Didn't cost you anything except a few minutes of your day. Hell, sign up too Irok, if you win, you can play or give it to Ryat and make him play. 
