Let me lay down some EXPERIENCE with the Yokomo.
a) the "DRIFT PACKAGE" is fine out of the box. You NEED no upgrades to drift nor to drift well?
b) Yokomo is expensive and parts are normally only attained through the internet. Reason being (for the parts) there aren't a lot of LHS's that carry them outside of Japan and Cali, USA. However, their site is easy to navigate through and their customer service is the best in the business. No company comes close to them on that aspect. HPI's sponsors our team and I STILL don't get the great service from them that I get from Yokomo. They're expensive because they're one of the best around. Arguably the best still produced. Yes, there is the TA03F, but as we all know, it has been long since discontinued.
c) Like redeyes said, there's a reason why the best teams in the US AND Japan use a lot of Yokomo products. If we check any of the top teams, you will find Yokomos. That's a FACT! Not to say that there won't be any other car makes, but it's a top competitor and it's that for a reason.
d) any 4wd chassis can drift, tis true. Practice is what makes you good; not the car. However, you take two people given the same skill and same practice time and give one a Yokomo (even the basic drift package) and the other some other chassis (stock, like the DP is), you'll be hard pressed to find a chassis still in production that will beat it.
e) the DP is STOCK!!! It is the BASIC DRIFT PACKAGE OFFERED FROM YOKOMO! Stop comparing it to chassis that come with everything. You're comparing apples to oranges. Compare it with another BONE STOCK BASIC BOTTOM OF THE LINE package, whether it's stamped as "drift" or not, and tell me what chassis will hold a candle to it. I've seen none. I don't know of ANY chassis, "drift" or not, that you can take out of the box, stick in a battery, and drift WELL. There may be one. I haven't driven every chassis. I'm sure a few people will pop up on here praising their UBER MODDED tt01 or tc4 or TA03F or Sprint2 or WHATEVER, but I've yet to see one come out of the box as well as the MR4TC DP.

And for the record, I outdrifted quite a few people with quite a range of cars with a bone stock DP. I had the out-da-box setup for almost 2 years before I swapped out ONE SOLITARY PART! I didn't upgrade because I had to. I opted for a faster motor when our team was going to D1 and I just decided to do a stage1. And I might change back to the softer springs because they're more forgiving on concrete and allow more play on carpet. Also, I'm not exactly sure where this whole "Yokomo's break a lot" came from, but my car has NEVER broken. I dropped some books on it and cracked the CM chassis, if you wanna call that a break. But it was a bookbag full of COLLEGE books, and we all know how heavy those are. And, I've yet to hear of anyone breaking one. Not a ONE. And I can get about 100 guys to collaborate on that.

All that being said, get what you can afford. Yokomo IS expensive and I'll never say it isn't. I wouldn't recommend it for someone who only wants to do this occassionally, by themselves, as a part time hobby. It's a serious car (not that it's the only one) for those who really want to get deep into this. There are PLENTY of capable chassis out there that are less expensive. They may take a little more work to get them to do what you want, but they're out there. I'll personally vouche for the TC4 and the TT01. I had a TC4 and 2 people on our team have TT01's. Matter fact, one of them is the D1 East Coast champ.

Whatever chassis you like most is usually the one you'll vouche for. Very few people will give you an honest opinion on a chassis that they don't like or don't use (as I'm sure my analysis is biased on what I like). I don't like the TA03F because it's discontinued, expensive, belt driven, and better than my fav. But, it IS better than a Yok. But, good luck finding one and parts for it. I really don't like the TT01 either, but it's a great car for only a little bit of $$$.

That's my $0.37