With UI design in particular it's a killer. it actually requite good technical knowledge, good visual sense, good psychology background, understanding of business objectives... It takes that special person who can think in an interdisciplinary way, and that usually isn't cheap or easy.
You frequently don't get what you pay for - there is very little correlation between price and quality.
Take Drupal for example - cheap AND good. Compare with our new Mega Corp CMS which had a 7 figure price tag and a work flow so atrocious it had to be scrapped before deployment was complete.
If you want good products then by picking something that is already good and only requires minor changes you have a pretty decent chance at a fair price (which might be high or low).
"there is very little correlation between price and quality".
to a point. While design can often have a rang of price there can be a clear difference between paying some one a living wage and not. This number can vary international but it's good to know what is considered a professional wage abroad.
Also price can have a high correlation to experience. More experience is good if you care about the details but many rather stay cheap.
the design field is changing and there is a lot of price fluctuation and it can be hard as a company to gauge if a company is worth the price. But to say there is little correlation is a little misleading.
This really depends what you mean by cheap. If you're the end user then yes, it's cheap. However, Drupal has had a lot of time and effort put into it. The important correlation is between that time and effort (and the quality of those putting in that time and effort) and the quality of the product.