I was looking just for a very simple approximation, and your ballpark estimate of thousands is good enough to me. I was looking for a way to understand the difference in complexity (in terms of number of instructions) between RISC microcontrollers with their 100 or so instructions and general purpose CPUs like the i7...
Since i7 is based on IA-32 Intel architecture , you can find this information in the IA-32 architecture data-sheet's instruction set reference section http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf.
Keep in mind that this architecture is complex and that there are up to 12 types of instructions. Some are, as Peter had mentioned, just slight variations of one instruction etc. But however you wish to "count" them, you can use this manual and material therein for reference.
I have counted 338 individual instructions, but some might be copies or aliases (for historical reasons) or just slight variations (whose use depends on circumstances such as safe mode on-off, virtualisation on-off etc).
Here is the full list I've assembled from the datasheet: