I can understand being frustrated with rising prices, especially with tunes. Tunes aren't affected by the cost of raw materials, shipping costs, customs fees, or things of that nature. However, let's take a look at Greddy and HKS since you used them as an example.
The HKS Carbon Ti catback has a retail price of $895. It had this same retail price back in 2002, and the price didn't go down, nor went up. Add in the rising price of aluminum, carbon fiber, and oil (for shipping) and one would expect this price to go up, but it didn't. Thus, HKS was okay with making less proft margin on their exhaust despite their cost of manufacturing and shipping going up quite a bit. Moreover, they haven't changed their discount level to their dealers either, so dealers are still able to sell this exhaust for less than $895.
Greddy on the other hand, has also kept prices the same, however they cut dealer discounts, in the name of curbing Internet price wars. Thus, a dealer who used to get 35% off retail would then only get 20% off retail. By doing that, in essence all selling prices go up, but they don't go higher than than MSRP, plus dealers can no longer ***** out Greddy's products. Many people associated this with Greddy pricing going up, but in reality it really didn't. In fact, the only real price increase Greddy's made over the past 2 years has been maybe $10 or $20 to help account for the higher shipping costs from Japan.
Now, this issue with price whoring seems to be something that no one (not even Greddy) has been willing to mention as part of their demise. Why? Because it alienates their dealers and their customers. Dealers don't want to be called out for whoring out prices, and consumers don't want to be called cheapasses either. This is a problem that Greddy had way before there was any sign of financial crisis, by the pure and simple fact that they did not enforce any type of Minimum Advertised Price (MAP) policy on their dealers. Please don't get this confused with price fixing...price fixing is illegal and by law, it's defined as a company (or the government) fixing a sale price on a product or service, with no freedom of selling higher or lower than that price. MAP only refers to advertised pricing, whether it's on a forum sale, on a website, on eBay, or in a print ad. Many companies are very strict on MAP policies, including Cobb Tuning, Kartboy, and AEM...and by them staying strict on it, the value of their product stays consistent and dealers do not ***** out their products, which is what has plagued Greddy for quite a long time.
Finally, I don't believe it's a fair to compare a $200 exhaust that you fabricated yourself to an exhaust from Greddy or HKS. You 1) have the know-how to fabricate it yourself and didn't have to pay someone to do it, 2) don't have to pay for distribution of your exhaust worldwide (which includes shipping, packaging, and customs fees), 3) you didn't have to pay for marketing the exhaust, 4) you don't have to pay for mass production of the exhaust, and 5) you probably didn't come up with several different designs and test all of them to figure out which either flowed the best or gave the best balance of flow, sound, and looks. But, let's say that you take all of these into account and maybe (hypothetically speaking) the final cost with everything above included comes to $450. Is it fair for a business, no matter who big or small their are, to sell this exhaust for say, $500 MSRP? Or maybe even $550? That leaves absolutely no room for any wholesale dealers, so it'd be direct from the company, and only direct from the company. Put it together with an average of $50 shipping for a full catback exhaust, and you're at say $600 total. Now, let's say you want to give enough room to do wholesale, since it's hard for a company to do all of their sales without some type of distribution. In order to give a wholesale company even 10% margin and for you to make 20%, you'll need to raise the MSRP to about $650. But wait! The Greddy Ti-C catback has an MSRP of $635, and the HKS Hi-Power has an MSRP of $625!
Anyway, the exact pricing to the cent isn't the point. The point is...costs go up very fast once you start aiming at a global market. If you want to make your own exhaust to save money out of your own pocket, more power to you, but it just isn't fair to compare it to a business that has overhead, shipping, materials, and marketing costs to account for. After all, your mom can knit you a sweater for free, but you're not going to be able to sell that same sweater without a lot of added costs involved.
Since we're on the subject of exhaust pricing, here's some more food for thought. People balk at the price of Greddy, HKS, or any other JDM exhaust, but the same people who complain about "paying for JDM bling" have no problem paying $675 + shipping for a Cobb Tuning catback. It's not like the welds and finish are 10 times better on the Cobb exhaust compared to the "JDM bling" exhausts. In fact, often times I've seen better welds on the Chinese-made Invidia exhausts than on Cobb's or any of the JDM exhausts. Thus, what gives here?