Exactly what i am trying to say. You can get two 1TB HDD and run them in RAID 0. The write speed will be boosted up to the 2x HDD max speed. So lets say we have:
Seagate Barracuda 7200.14 (1 TB, 7200 rpm, SATA 6 Gbit/s), for the price of 115.94$ (Offer from AMAZON:
Click)
We will have max write speed of 205.73x2 = 411.46MB/s.
Tortal spend will be 230.88$
Total Memory will be 1TB.
So its easy to see that we have Double amount of memory for almost two times less money and almost same performance (the difference will be 5~15 seconds particular operation).
Ofc ther is no way to make HDD configuration which can get even close to SSD's IOPS number but for home use this does not matter at all.