car seats

I am debating on what car seat to get Nash. It is Arkansas law that a child has to be one year and 20lbs to face forward. Nash is now 20 lbs and his current car seat goes up to 22 lbs. So, I am thinking about buying a new convertible car seat that can face forward and backward just in case he outgrows his other one. That is another issue I have, how will I know if he does not get weighed again unitl he is a year? but I would imagine he would not gain much more than two pounds in three months, right. I guess I could always take him in to be weighed. ANYWAYS. I have done some research and found the "top" recommended car seats BUT I want to wait as long as I can to switch out car seats because his is so convenient to take in and out. With a new car seat, it will be harder to get positioned each time. The car seat base combo is really easy and convienent. The convertible seats are big and bulky and have to be fit into the car and latched in making it more difficult to take in and out. The convertible car seats that are recommended vary greatly in price. The most expensive one is over $300 and the cheapest one (in every sense of the word) is $50. So, I am trying to make a decision on which one to get. I have had some people recommend certian car seats and that is helpful because then I can research that particular one. I have heard good things about the Sunshine Kids Radian 80. It has a lot of safety features (mainly a steel frame where others have plastic) and has the highest weight limit (up to 80 lbs so you basically would never need another car seat). It is the one that I am leaning towards. The most popular and most expensive one right now is the Britax Marathon Model. You can often find them in local stores where the Sunshine Radian you have to order online but it has free shiping and is not as expensive. I feel there is a lot of pressure about car seats because of course you want you child to be as safe as possible and they kind of get you on that point. All car seats pass the federal guidelines but some have extra safety features or bells and whistles that are nice like easy adustable straps or straps that don't twist or extra comfort. Like everything else regarding Nash I am way overthinking it. The main thing I am battling with is the Britax model versus the Sunshine Radian. I have heard good things about both but leaning towards the Radian due to the safety features, better price, and long use. If any of you have any suggestions or advice of course I would love to hear it.