It's ok but you can do better.... I would cut it down to at least "Because I was unable to afford a house, I ...." .... "afford to buy" is redundant. "Afford" already carries with it the implication of "to be able to buy" so you can just say "afford" -- GOOD speakers would do this, although you'd hear people throw in the "to buy" as well. I suggest you just use "afford" --
best imho is "Because I couldn't afford a house, I ...". This allows the useful word "afford" to carry all the weight that God intended for it .