In biblical times, betrothal was as binding as marriage. Our Orthodox wedding ceremony begins with the betrothal ceremony. My question is this: would it be possible, or is it ever practised that a couple who maybe isn't ready for some reason or another for the full wedding ceremony-maybe for financial or other reasons, I don't know-to have a private betrothal service and then start living together (and to have the full marriage ceremony, reception etc., later)? I hope this question makes sense...
If my (very likely wrong) understanding is correct, (NT times) Jewish marriage was natural, and not Sacramental/mysterious. A man would be betrothed to a virgin, and she would go to life with him in his house. They were basically married, but had not yet consummated their marriage, often because the girl was too young. When she was old enough he would take her to him as his wife.
In Orthodoxy marriage is a mystery. Betrothal binds the two together, but they are not yet in the sacrament of matrimony. They may not have marital relations or live together. In the Coptic church, the betrothal service is almost always done before the wedding (usually about a year), and includes prayers asking God to help the couple remain chaste until their wedding. I don't know the history of the purpose of this service, but this seems to me to be it's purpose today: it legitimizes the relationship between the two as they prepare for their wedding, and asks for grace for them to go through that difficult time in purity.
I think the only answer to the problem in the OP is that living together and having relations before the wedding are not options. If a wedding is not possible because the ridiculous $20 000 average cost of a wedding today is not financially possible, and if waiting in chastity until it is is also not possible, then there is a choice: either choosing the cultural norm of the expensive wedding at the expense of chastity, or forging the expensive wedding, and marrying simply without a diamond ring (only the bands are needed), limo, expensive dress (a simple on will do), and reception with flowing alcohol.
I know that practically speaking it is not that simple. Family pressures to conform to social norms can be very difficult, and should not be ignored outright as any bending to accommodate strong requests of parents is good as long as it does not lead to greater sin than the offense of not bending. But while it maybe be really hard, I really think that that is what the choice comes down to (if I have even understood the issue here).