I've only read a little about Bohme and none of Luria. I wouldn't surprise me at all they speak of God in similar ways as mystics. I'm not sure if Eckhart actually stated this but it is attributed to him nonetheless, "Theologians may quarrel, but mystics the world over speak the same language".
Can you summarize what Bohme and Luria say that you are hearing as similar?
It is a nice quote and true, however your suspicions are right. Meister Eckhart did not say this, the modern Hindu preacher Eknath Easwaran - who passed away in 1999 - said it in his book
on Meister Eckhart and Christian mysticism, see here on google books:
Original Goodness: Elknath Easwaran on the Beatitudes of the Sermon on the Mount - Eknath Easwaran - Google Books
Being familiar with both his works in the Latin and in the German vernacular, it just didn't sound like very Eckhartian language to me either. A medieval Catholic schooled in Scholasticism would not have spoken that way.
A later Catholic mystic did say this though, which is pretty similar:
"...All mystics speak the same language, for they come from the same country..."
- Louis-Claude de Saint-Martin (1743 –1803), Catholic philosopher, mystic and theosophist
Saint-Martin was the first person to translate the works of Jacob Boehme, ironically, from German into French.
I think this is the actual origin of the quote surfing around on the internet which purports to be from Eckhart. Whoever read it must have thought, "Oh Catholic mystic said this..." and then it got garbled through the Chinese whisper effect and somehow became attributed to Eckhart.
Doubtless Eckhart would have agreed though, for he did say this on a Treatise on Detachment that was written either directly by him or by a close disciple:
"...I have read many works of both pagan masters and prophets, and books of the Old and New Testaments, and have sought earnestly and with the utmost diligence to find out what is the best and highest virtue, with the aid of which man could be most closely united with God, by which man could become by grace what God is by nature, and by which man would be most like the image of what he was when he was in God, when there was no difference between him and God, before God had created the world. And when I search the Scriptures thoroughly, as far as my reason can fathom and know, I just find that pure detachment stands above all things..."
- Meister Eckhart (c. 1260 – c. 1327), On Detachment
He was ecumenical minded.