You have to be careful with adjectives (and their associated o-forms) when they are prefixed with не-. Some such words have a pejorative meaning, correlating with English un-, e.g. неприїтный 'unpleasant' and others have a more positive connotation, like небольшћй 'not too large, rather small, modest.' To be safe, consult the dictionary.
The word небольшћй is a good word to use in order to avoid the pejorative connotations of its near synonym мђленький 'little'. Compare:
Ћн живёт в мђленьком дћме зђ городом.	He lives in a little house outside of town. (The poor guy!)
Ћн живёт в небольшћм дћме зђ городом.	He lives in a modest house outside of town. (It's a nice place. Not too big, but nice.)
Thus, some adjectives with не- are not truly negative, at least not in their connotation. The true negative particle не is written with a space:
Егћ дћм не большћй, а мђленький.	His house is not big, but little.
У негћ небольшћй дћм зђ городом.	He has a modest home outside of town.

Here are 4 words to evaluate prices, listed from cheap to dear. Note that English words such as 'pretty, not too, rather' render this meaning of не fairly well:
Јто дёшево.	Јто недћрого.	Јто недёшево.	Јто дћрого.
That's cheap.	That's reasonable.	That's pretty expensive.	That's expensive.
	That's not too bad.	That's not too cheap.
Here are the o-forms of two words you know (плћхо and хорошћ), with and without the 'nice' prefix не-:
Јто плћхо.	Јто нехорошћ.	Јто неплћхо.	Јто хорошћ.
That's bad.	That's rather bad.	That's rather good.	That's good.
	That's not too good.	That's not too bad.