Good pastels aren't exactly inexpensive, but buying low-quality pastels isn't a good money saving strategy, so are some ways to help your pastel budget go a little further.
Go halfsies! Half-stick sets are a good way to get a larger variety of pastels for less money.
Share and share-a-like: If you're a painter that cuts your pastels in half, try cutting your budget in half too by splitting a set with a friend. More colors for half the price!
Wait for a sale: Pastels do go on sale and waiting for special offers can save you quite a bit. Around the holidays many manufacturers and art supply stores have discounts, which consistently makes November and December a great time of year to treat yourself to a new set. Sales happen throughout the rest of year too, so subscribing to newsletters, emails, and social media accounts for pastel retailers is a good way to learn about sales.
Buy second-hand. This can be a great way to snap up some pastels on a budget. Artists who are now focused on other mediums or who bought a set they don't personally enjoy, occasionally sell sets to recoup a bit of their investment. Look for them at art supply swaps or even online (buyer beware though, it's hard to tell from just a picture exactly what you're getting). Be cautious of tag-sale buys, you often find very old pastels there, which can be tricky. I know a lot of artists who've bought very cheap pastels at tag sales; some have scored, others not so much. If you want to know more about why old pastels can sometimes be problematic, read my post about Vintage Pastels.