But, E-bay and alot of anime "import" stores do just sell bootlegs. Especially if its in a china town.
Know your DVD!
If you have in mind how the primary and reversable cover (if appliccable) of the real DVD looks, you won't have a problem. You can find these on the bandai site. (www.bandai-ent.com)
With that in mind, you'll be able to spot some of the outright fakes just by cover design.
but, what if you can't remember? Well, check the information on languages and region. The following information usually appears on bootleg DVD.
Region 0/ All Region/ Region Free
Japanese Language, English/ Chinese Subtitle
Remember... If it's an E-Bay item and it says "HK" or "Hong Kong Edition"... that's like saying "BOOTLEG OVER HERE!!"
Also, know your disk quantity. Gundam 0083 for instance was a 4 disk series. On E-bay, people sell "SPECIAL 2 DISK COLLECTOR EDITION!!" which also, funnily enough, has the region 0 part on it.
Bandai do NOT release region 0 DVD because they can make money with region coding.
Also, look at the box. Bandai DVD will have either the bandai logo on them or the Bandai shaped words with "Bandai Entertainment" on.
If you live within England or the United Kingdom, and perhaps some parts of Europe, your distributor is known as Beez, not Bandai. It's okay, Beez has the license to release Gundam on our shores. It's the real deal.
Also, remember boxed sets. Look at them. Let's take an example, now.
Gundam Wing box set....
This is the real one.

Language English/Japanese
Subtitle English
Format DVD
Running Time 1225 min
Suggested Age 13up
Episodes 1-49
Price $199.98
This information came from Bandai-ent. The box is an image of one side only, so you can't see the bandai logos. The DVDs inside look like the normal set.
Now, onto E-bay. First auction I see.

"Buy it now" price: $42.99
Complete TV Episode 1 - 49 complete + OVA ( 7 DVDs )
English/Japanese dialogue with English subtitle (on/off)
Region code: all code, region free
Video : 4:3 Letter Box
Audio : Dolby Digital Audio
Item is brand new, sealed, never been used
Compatible with Playstation 2
Things to note: can see the WHOLE box set. No bandai or bandai entertainment logo. No sunrise logo. Unidentified logo on top of DVD case (fake manufacturer maybe?) Now, this one is english. That makes a nice change... Notice: Region code is free. Bandai don't do that. PLUS OVA?? The ova was made after the series. The box set was released before the OVA was. This suggests this is a BOOTLEG before we even go onto the price! Look at it. It's got MORE than the real one. But it costs LESS. You gotta wonder why that is...
Second E-Bay acution (first one with a different set)

"Buy it now" price: $33.00
Condition: 100% brand new, Deluxe packing
No. of Disc: 6, (1-49 Episodes )
Dialogue: English/Japanese
Picture: 4:3
Subtitle: English/Chinese
Region Code: All code, region free
Sound: Dolby Digital Stereo
Again, chinese subtitles, region free, LOW NUMBER OF DISKS, fraction of original price, no Bandai or Bandai-ent logo. This is ALSO a bootleg... But, i'll give them points for such a neat cover.
Okay, that's about it for DVDs... Any more queries, ask here and i'll try to answer.
Now, onto Gunpla (Gundam Plastic Model, Also known as Gunplamo)
The main MAJOR culprit of bootleg Gunpla is a company called Bendi. The box art looks something like it should do. They've taken to using the word GODA instead of GUNDAM now. Here is a FAKE Dinn found on E-bay.

He costs only $3.00, and copies the style of the "ungraded" bandai kits.
Here is an image of the REAL bandai Dinn

The box looks the same as the fake. Only the bandai logo and the name at the top are different. This one was on sale for $6.00
The real difference is Bendi kits are frequently poorly moulded and need alot of work to even be buildable... and with the bad quality of the "ungraded" bandai models as it is, the bendi "ungraded" kits must be 10 times worse!