That's the first time I've heard anyone say that studio monitors cost _less_ than consumer audiophile stuff.
Saying that as a person that buys and uses studio monitors, they are not cheap in any way.
Even "affordable" entry level stuff (eg JBL Pro LSR 305P/310S) is going to set you back a good chunk of change compared to consumer gear.
They're engineered to work together, and while you _can_ go without the sub for a while... it's a shit setup and only useful in the short term.
Wouldn't want to be doing production stuff (or even end user setup) without the sub. ;)
One of the thing that's interesting to note with monitors is how 'biased flat' is very much a thing and that consumer audiophile speakers are very much not always biased flat, I think the varying companies have a sound profile which they aim to target.