In regards to FourAces' question, "As far as STUDIO strobes, I'm reading a book that "recommends that your purchase at least four self-contained units, such as... the X Series from Paul Buff ($399 and up).What do you guys think about that?"
My personal preference is not for self-contained strobes aka monolights, but rather pack-and-head systems. Monlights are very expensive per watt-seconds; I think a four-light portrait setup is pretty standard; main light, fill light, grid-and-barndoors equipped separation/hair light, and a background light; often times two background lights are needed to easily and smoothly elevate large gray backgrounds up to white or lifting a black seamless up to gray. With a low-cost power pack,like a used Speedotron six-outlet pack like a used 2401B for $500 and four used 102 or 103 heads, you have the ability to light sophisticated setups pretty easily.
Monolights get very expensive when you need four or five or six of them. Power packs these days are very low-cost on the used market, and many brands have ample accessories designed for professional use and long life. I know a lot of beginners and hobbyists love Alien Bees and White Lightnings, but I got into studio flash before the Bees were invented, with the most popular studio flash brand in the USA, which is Speedotron. For beginners, there is no better value than Speedotron; it's a system that has compatibility dating to the 1960's right up to the present day,so there's a ton of used equipment available, very cheaply these days with the lousy economy and all the commercial studios that have folded/are going under, liquidating their lighting gear.
If you go with the lower-cost Brown Line power packs and heads, you can buy D402LV power supplies for $100-$125 on
eBay every week,and light heads with 400 watt-second flashtubes are selling or $50-$65 on
eBay quite often. D802 800 watt-second Brown Line power packs are very affordable on the used market. If you need say, 1600 watt-seconds fired through one light head, a D1602 power pack and M11 light head is very cheap on the used market ($75 used, $225 new). Same with the D604 600 watt-second, four-outlet power supply.
With monolights, high output level monolights cost a veritable fortune compared with used Speedotron Black Line packs and the "standard",cheap 102 or 103 light heads. With a 2400 watt-second six-outlet pack, you can fire 2400,1200,800 watt-seconds through 1, 2, or 3 light heads--or 400 through six heads. For portrait work, with d-slr cameras, as little as 50 watt-second per head is often enough for fill and hair/separaton lights, so the cost of three or four monlights at $350-$400 each is wasted money that would be better spent on quality light modifiers and a decent boom stand and some good light stands and some accessories like grids,barndoors,and scrims and reflector cards.
I will re-state that last point again: for portraiture of singles and couples,you are wasting money by purchasing four, 400-watt-second monolights because as little as 50 to 100 watt-seconds is often all you need for one or two of the lghts,especially with new d-slrs that have a base ISO of 200. SPLITTING 400,600,or 800 watt-seconds through three, or four light outlets on a power pack is all you will need for many shoots.
If it were "me" I would investigate the pack-and-head system by talking or corresponding with somebody who has experience with pack and heads. Monolights have some advantages, but buying three or four matching monolights might not really be as economically feasible,or flexible, as buying a pack-and head system that has ALL the accessories you will eventually want.
Dropping $1600 for four $399 Paul C Buff monolights would mean foregoing a MUCH more-complete,broader, and more-capable Speedotron system that would have higher output, more outlets, and more options, at a used cost of $1,000 or so for the entire Speedotron system--maybe even dramatically LESS than $1,000 if you score some good buys and choose wisely. Like I said, used lighting gear is extremely affordable these days...and with Speedotron it usually has years of life left due to the design and build quality of every item in the line.