I personally like the KRK & JBL line of monitors. They both have bitchin' subwoofers also available to complement their compact monitor speakers that are self powered, all of them. For your stuff, yeah. I'm not much on using subwoofers myself since my mixes are already quite punchy. Though I have worked with the KRK subwoofer with a pair of V. 88's but I find myself regularly switching it off to do my mixing and only turn it on as a playback reference as to how it might sound that way after I'm done mixing. And sometimes I mix with it.

I'm consistently inconsistent
Mx. Remy Ann David

Which models would you recommend?

Hope to find some good used ones for $200 or less

$200 or less? For both or each? Including the subwoofer? I think you're dreaming? It's after your bedtime. I know the KRK RP 5 series for a pair is around $300 and no subwoofer. I've equipped two clients of mine with those, no subwoofer. There is other stuff out there but you're not going to find much for $200 for a pair that's worth having. $200 each, oh yeah, no problem there. Perhaps you should just start with a pair and purchase the subwoofer later? Their subwoofer has some nice tricks built into it which also then becomes the central distribution point for the other two monitors. It's cool and solid sounding.

KRK V6 & Rock-it's in control C.
Mx. Remy Ann David

200 a pair...lol

My room is about 10 ft. x 15 ft.

What size monitors do you recommend? 5,6, or 8? Is a subwoofer really needed?

The monitors will be placed about an arm's length away.

Even in the space that you indicated, bigger is better. Though I would have no problem and have used 5 & 6 inch monitors largely without subwoofers. Pretty much my favorite sized monitor is an 8 inch. Never mind that I typically use in my control room 12 inch old-fashioned rock 'n roll JBL 4311/4312/4411. In Control A, I am utilizing 6 inch KRK & Bang & Olufsen in the Surround Sound control room and just stereo in the main control room. I'm actually quite fond of the Surround Sound control room even without a subwoofer. If the room has some unflattering nodes, you may find a greater need for a subwoofer? And/or some acoustical treatment including bass traps.

I fully believe you could probably find a pair of KRK RP 5 series monitors, used, probably within a $200 budget?

You'll find them I'm sure.
MX Remy Ann David

Do you know any other marketplace besides Ebay and craiglist?
~200 is my budget

You might be able to find a pair of Event 20/20 BAS but they'll be passive and you'll need an amp of some sort for power. What you're asking for is almost non-existent.

Um... you might check your local newspaper classifieds? You might want to check with your local university/college music departments as they frequently turn equipment over? You could check with your local churches if they happen to have any small monitors that they are not using? And as Dave dog suggested the Event 20/20 are actually quite fine sounding fairly impressive. You could utilize an old stereo receiver/amplifier which would probably serve as a reasonable power amplifier to drive something like that as long as you've got at least 40 W per channel of continuous RMS output. Speakers are generally more different sounding than most average amplifiers. Though I can tell you, even if this is beyond your scope, a classic Macintosh amplifier with its huge Output Autoformers (Basically a transformer or least half of one) sounded nothing like the direct coupled classic Crown D-300 A. Although I have found most average Japanese stereo receivers don't sound terribly different from each other and can still make for a decent amplifier. One of my playback systems in the secondary control room are powered from a simple JVC AM/FM receiver/amplifier. I actually like the JVC sound, not precision but also quite adequate for rock 'n roll.

$100 per speaker could get you a usable pair of monitors if you already have a stereo amplifier.
MX Remy Ann David