That cage is a good size for travel, outings, sleeping, ect. I think you actually got a really good deal getting it for only $27. But... it looks to be about 18x18". A cockatiel's wingspan is about 18" so he can't even open his wings in there without hitting a toy. If he is spending a lot of waking hours in there, he really should have a larger cage.
A flight cage is ideal - they're around 32x21" so quite a bit larger, but they are an overall very good value for a cage and large enough for him to be active in the cage. They usually cost around $125-150 including shipping, depending on sales.
Also, you'll want to provide some more perches - especially if you get a larger cage. Dowel perches themselves won't harm their feet - but sitting on perches that are all the same diameter will eventually cause discomfort (and even arthritis eventually - but that takes years). The best perches are simply fresh cut branches from a tree (make sure it's a non poisonous tree). Natural branches will have natural variations in diameter and are good for their feet - plus they like to chew on the bark. You can also buy natural branch perches if you can't cut your own. Some birds also love rope perches which most pet stores should have.
I would try replacing the top dowel perch with a natural branch perch and perhaps add a small rope perch. He will probably only use the lower perch for getting to the food and water, so leaving the lower dowel perch in is fine.
If you get a larger cage, which I hope you do, you'll want to get some extra perches or ladders to help him get around and use the space, especially if he's clipped.