That is true, your budget also limits your choices however...
so why don't try linksys ea3500? It is
- Dual band
- Gigabit ethernet port
- USB
- 64M/64M
- Sleek and curved no atenna design
- Cheap as less than $20 on eBay
- Easy to flash through web interface
Most people have not known its value so it is on good price now. Once more ppl buy it for second hand the price could go higher as other TP-Link crap.
hard to find in France...
a least +20 euros for shipment cost...
but I keep it in mind thx a lot
A bit expensive in France.... I know, I know 
Single band, in EU look for a TL-WR842N v3 (EU). I think these are (or were) only sold in the EU and were relatively cheap. This is one of the fuller models among the entry level TP-Links-- it has Atheros chip, 16+64 memory, and USB.
My current favorite model is the Netgear R6100. Don't be put off by the internal antennas, it has very good radio performance that is comparable or better than most external antenna routers.
What about Archer C20i
seam to be supported...
https://lede-project.org/toh/hwdata/tp-link/tp-link_archer_c20i_ac750_v1
but some had trouble with it
EDIT:
Seams to be quite well covered in OpenWRT Wiki
https://wiki.openwrt.org/toh/tp-link/archer-c20i
What do you think of it ?
Cons:
- mono core
- 100 mb LAN
- crap 5GHz is not supported according from toh
70 euros from ebay Germany.
The TP-Link Archer C59 might come close to your requirements (starting around ~35 EUR, concurrent dual-band, 100 MBit/s ethernet), although I would recommend against buying non-GBit/s ethernet devices these days. Flashing is said to require tftp, but should be rather straight forward.
Disclaimer: I haven't tested this device myself.
looks like a satellite lol
Yes I can get it on Amazon for 35 euros but OpenWRT wiki says WIFI 5GHz broken and 2.4 is very bad... So it's a no go for now... Too bad it's a good device on paper.
Ar300m seams a good product I've found one for 46 euros on Amazon
What's the difference between nand and nor support ?
TP Link TL-WR810N V1.0 seams pretty close ?
NAND is not available in LEDE, but there are precompiled "clean" versions (no GL.inet GUI) for NAND and NOR memory available from the GL,inet downloads site. I think there are also tools to roll your own, but it's not something I do.
There is a dual external antenna version available from the GL.inet store, not sure about your market.
Thats old info, also the forum discussion is half a year old. Wifi is fixed in latest snaps. (Archer C59)
For which device ?
Why is nobody recommending the D-Link DIR-860L rev. B1?
Dual-band and dual-radio 802.11ac, gigabit Ethernet, USB 3.0, and it's available on Amazon as well, although (like everywhere) you'd need to check whether it's rev B they're carrying.
Granted, it's not 35 €, but in that price bracket you won't find a dual-radio 802.11ac router, let alone one with gigabit and USB 3. Reality check 
.
At that price you can find ARM-based devices (new and refurbs) that performs better....
raspberry pi's work great, does the raspberry pi 3 have gb networking now?
The Pi3 is not ideal for networking. Everything in or out of the CPU is bottlenecked through one USB2 port. Also the wifi chip is 2.4 only, Broadcom, with 1x1 tiny antenna.
guess ill rule that out and just use an raspberry pis as an mpi cluster and 2 new pci antennas on a desktop server or something.you can buy boards for multiple lan hubs btw.
Which ARM based device can you find at that price that performs better (including throughput and WIFI performance) ?