If you're a newcomer to the hobby, spending more than necessary, not getting the best deal or simply buying a product which looks promising, but will not deliver is easy.
Links open in new tab, contains Amazon affiliate links (you pay the same price and may get free shipping in the USA), legal bits here.
Buy from manufacturer
Nooelec and rtl-sdr.com are popular and well-known makers of RTL SDR dongles, both have a webshop (Nooelec, rtl-sdr.com), both take credit cards.
Also with eBay presence, always check the seller name:
Other sellers try to capitalize on the brand name, price will be higher, 30-day returns:
Same dongle can be ordered for $38 from Nooelec or for $36 from Amazon. With 2-year warranty, not 30-day returns.
v.3 is quite popular as well:
Same dongle costs $25 from Manufacturer or $26 from Amazon.
One more example:
Buy from manufacturer, or via official distribution channel on eBay - check the seller name.
Eight to 12 dollars for generics
Unbranded dongles should not cost more than $10 with free shipping from China or the Far East:
Four common and recommended choices above, search for "RTL-SDR" or "R820T2" (which is a better chipset) on eBay, know that shipping can take 2-3 weeks, if impatient, a generics is yours for $13 from Amazon.
Or pay double:
New advanced? Architecture is more than two years old. New antenna? That antenna is sold for years. In fact, dongle above is same specs as a Nooelec Mini 2 for $18 from manufacturer or for $21 from Amazon, but after seeing what's inside these generic wonders, I doubt it will be as reliable as a Mini 2.
Ship from US
A new and recurring theme is increasing the price just because an item ships from the US:
Newsflash: rtl-sdr.com, Nooelec and Amazon also ship from the USA.
Warfare for your wallet
Read some Philip Kotler just for fun for more information - linked textbook is highly recommended as one of the best in the field to understand how marketing works.
Online sellers most definitely and carefully studied the chapter on Price, or read psychological studies, because you can get a receiver for silly money.
Receivers above are the four main types coming up in search results. A customer who knows nothing about radio, but wants a good solution to a problem, will identify higher price with higher quality, so will click, then the buying impulse will be reinforced with additional information:
The vast majority of these Full-Band receivers are plain vanilla RTL-SDR dongles in a metal case, with additional accessories. Full-band means that they use direct sampling, a method to tune below 30 MHz in software, a method possible with most $8 generic dongles after inserting a wire into a particular hole (my guide here) or with the rtl-sdr blog v.3 dongle.
Buying impulse still lingers, but our imaginary customer wants to save. Who doesn't? Keep browsing mate, you'll find a cheaper price:
Saved more than 50%. Feels good, isn't it? Let me ruin your day. You've just spent 34 bucks on a metal case containing a four-year old tuner, an antenna which will only really work well on one frequency, a crappy USB cable and a magnetic mount which cannot be placed outdoors due to weak magnet and narrow base.
Significantly better choices for less money: either a Nooelec SMArt or v.3 in a bundle, for around $25.
Devil in the details
Product descriptions on eBay is a goldmine of laughs, and not just because of grammatical errors:
Referring to the R820T as an upgraded E4000 is a blatant lie; company manufacturing E4000 went out of business. Furthermore, an E4000 is much better than an R820T or T2 on certain frequencies, but that's a different story.
Can I jack up my car with it?
Probably. I doubt it, because the ad is for a Terratec, which is as generic as a generic can be. "Custom" and "tuned for SDR" is certainly not true, if a dongle comes with a remote, it's not designed for SDR, it's designed for DVB-T - read my RTL-SDR dongle generations for more info.
Keep it simple. F type is the (best). Period. Search for Patriotwaves on eBay for more pearls like the one above. I've included their products earlier in the Ripoff series, so they changed some of the descriptions, but every time I feel under the weather I just remember "TCXO RTL-SDR DARK KNIGHT DRONE DUAL RADIO RIG" for $50: get two non-TCXO dongles and a tripod. It's a "drone radio rig" because, according to seller, it resembles a drone.
In product description of $90+ Full-Band receiver discussed above. Image shows receiver only. No cables or antenna. Ripoff of a ripoff.
And some happiness
This is not a ripoff, included to show that proper (and innovative) sellers still exist: one of them is novakx5, whose LNA and filter is in daily use and highly recommended, his latest low-noise amplifier and bandpass filter for airband with bias-T or external power options: