So lets look at it in numbers, and when I say numbers, I mean the amount of dollars you need to shell out to participate.
To get access to Elite today you'll need to shell out a whopping $150, that may seem a lot but the Alpha backers had to pay twice that. You see Elite chose a crowdfunding model where prices were set high so that only the most dedicated of fans would get access to the rough unpolished early product with the price dropping over time to let more sensible people in. The regular Beta continues this trend and will only cost $75 but you'll have to wait until the end of August to join the more hardcore fans in the Elite universe. The final release is also available for pre-order at $50 and with a release date mooted to be 'before the end of the year'. However, there's another wrinkle to this pricing in the form of the 'Expansion Pass' which guarantees you all future DLC for a one time $50 payment, the future DLC will include features such as landing in planets and walking around stations. The Backers who paid for Alpha and premium beta both get this bundled with their package, while everyone else has to back it separately. If you consider this purchase essential to your future Elite happiness then it makes the cost differences between the tiers a lot smaller. All of this is of course available from Frontier's Elite Store.
The developers of Star Citizen chose a pricing model that worked in the opposite direction with early adopters getting things cheaper and the prices rising, albeit not nearly as dramatically. When the original Kickstarter launched you could get the Digital Scout package for $35, which would include Alpha/Beta access and an Aurora starter ship with lifetime insurance. Then the prices rose a bit, lifetime insurance was removed and now you have to pay an extra $5 for a pass to get access to the Arena Commander Alpha so you pay $45 and get less than those early adopters. (All the same lifetime insurance probably isn't going to be the game breaking bonus some people think it is, I'd advise against paying a 100% markup on the grey market for a package with LTI). Star Citizen is clearly the cheaper option, as long as you avoid getting carried away and spending money on internet spaceships, it's important to remember that everything on 'sale' will be available in the final game for in game cash. The downside to cheaper is that the game has a lot more development ahead of it, it has a feature list that is huge, and it will be years before we get anything like a final release.
The truth is if you're unsure or on the fence then the value equation for both titles is becoming clearer and clearer over time and the downsides to waiting are limited. About the only thing left with a deadline is the Elite Expansion pack covering the DLC which won't be sold after the 29th of July. While it's no doubt intended to be a money saving deal it's a deal that'll take years to pay off, if you're still wondering about whether to buy Elite at this point you're probably not going to go all in on future DLC. Meanwhile Star Citizen has already taken away LTI & Alpha Access, and the prices won't be increased without advance warning, so if you wait for things to get more developed then the only real downside is that you might have to wait longer to get access to multiplayer (after several weeks, I'm still waiting despite being an original backer).
So if you're uncertain, wait, and if you really want to play a spaceship game now just remember there are plenty of great games already on sale, or even for free. X-3 Terran Conflict, Strike Suit Zero, Freespace 2 to name a few, and of course there are plenty of free titles too - if you're a fan of Battlestar Galactica you should immediately download Diaspora and live out your Viper pilot dreams. There's no need to rush into anything until you're sure what you want, leave the rushing in to the hardcore fans who have more money than sense (i.e. me).