Hatmaker got some interesting ideas in his products, but as already mentioned, either infinite intensity or Never gymless will be -much- better purchases for you, lower price, much higher value. So either of those books I would rank as number 1 thing to buy.
Then after that it honestly depends on your goals and your budget.
-If- you got the budget for it and the space for it a barbell and some weights is the best purchase you can do. You dont need anything more than that to have a good routine, also it will force you to learn to powerclean so you can do frontsquats which will be good for you. Powerclean, militarypress/pushpres, bent barbell rows, fronstsquats, those kind of things. Then you can add in a power rack and bench for benchpressing later when you get the money.
An cheap ab-wheel (either buy one for 10 bucks or learn to make a better one for free on Ross Emanits site), a doorway chining bar (or if you got the possibility a better chin bar) are cheap and very effective tools and if you can find some kind of "powertower" or the like with a combined dipingstation and chinupstation it can definitively be worth the space.
To have a medium weight kettlebell (16-24 or 32kg) or an adjustable olympic dumbell is great for much conditioning work.
Also since heavy bodyweight training variations can be great on a small space a weighted west and some flexbands to load these variations might be just what you need, or just go the weighted backpack route...
If you dont afford the barbell or want to suplement it with an effective tool a medium to heavy sandbag is a great alternative, not a punching bag but a bag filled with sand. Cheap and effective ways of making it is on Ross site to. The options for what to do with a sandbag is basicly endless, make a few, perhaps a 30kg, 50kg a 70kg and a 90kg (or just make one in the middle) and the options are basiscly endless, clean, shoulder, throw, walk with it bearhuged or over head or throwned over a shoulder for distance, load it up a platform and back down, press it over head, row it. Great grip developer to since you grip the bag in the cloth.
You can also fill a keg partly with water and you will have a similiar cheap heavy thing that is awkward and effective to lift.
Basicly both these things will be slightly more effective than the things in hatmakers bagworkout tape altough he got some interesting things to add in to.
A medball is great and there are tons of sites on the internet that describes how to make one for free, not a priority, focus on making a sandbag first.
Be sure to get a few worn out tires and fairly heavy sledgehammer for doing sledgehammer swings, great for explosive power, grip endurance, strength and conditioning! You dont need a tractor tire either altough the bigger the better, car tires -do work-, I live in a cramped apartment myself without a garage but keep my 16 pound sledge and a car tire in the attic, getting it 3 floors up and caring it out in the forrest to slam the tire is a part of the workout...
A decent jumprope and a quality pair of running shoes should round out your purchases...
So basicly if you are tight on budget be sure to get/buy/make 1. Never gymless by Ross Emanit (
www.rosstraining.com) 2. A medium sandbag 3. A chin bar 4. An abwheel
(If you go this route a kettlebell surely can be good to throw into the mix down the way...)
And be sure to be on the lookout for a cheap durable barbell set (preferably based on a descent olympic bar)
Check out
www.rosstraining,
www.dragondoor.com, the archives at
www.crossfit.com all the archives at
www.testosterone.net and
www.elitefts.com for all the ideas you need.
If you go the barbell route be sure to pick up the second edition of Starting Strength by Mark Ripetoe to learn the lifts corectly.
