自考本科要向主考院校缴纳学费是很多人关心的问题。回答这个问题并不容易，因为学费的具体数额会根据不同学校和不同专业而有所不同。但是我们可以通过了解相关政策和经验来得出一些大致的估计。

首先，大多数自考本科的学费是按学分收费的。学分是衡量学习工作量的单位，一般一个学分对应着16个学时。不同学校和不同专业的学分数会有所区别，但通常一个自考本科学位需要修满120个学分。也就是说，学费数额会根据学分数目来确定。

其次，每个学分的收费标准也会因学校而异。一些高等教育机构可能会将学分价值设定在几百元到一千元之间。这意味着，总学费将取决于你所选择的课程学分数目以及学校的收费标准。另外，学费还可能会随着时间的推移而有所变化，所以在报名之前最好去学校的官方网站或相关部门查询最新的学费标准。

此外，还有一些其他的费用需要考虑到，比如报名费、考试费、材料费等。这些费用也会因学校和专业而异。在进行自考本科报名时，一定要仔细阅读官方文件和规章制度，确保你了解所有需要支付的费用以及缴费方式。

总的来说，自考本科的学费是有一定差异性的，具体数额需要根据学校和课程来决定。如果你真正关注学费的问题，那么最好的办法是直接与所选择的主考院校联系，咨询他们最新的学费标准和相关费用信息。

In English:

"How much tuition fees do you have to pay to the main examination institution for self-taught undergraduate studies?"

Paying tuition fees to the main examination institution for self-taught undergraduate studies is a concern for many people. Answering this question is not easy because the specific amount of tuition fees will vary depending on different schools and majors. However, we can estimate some approximate figures by understanding relevant policies and experiences.

Firstly, most self-taught undergraduate programs charge tuition fees per credit. A credit is a unit that measures the workload of a course, generally equivalent to 16 hours of study. The number of credits may differ among different schools and majors, but typically a self-taught undergraduate degree requires completing 120 credits. This means that the amount of tuition fees will be determined based on the number of credits.

Secondly, the charging standard for each credit may also vary from school to school. Some higher education institutions may set the value of one credit between a few hundred to a thousand RMB. This implies that the total tuition fees will depend on the number of credits you choose to study and the tuition fee standard of the school. Additionally, tuition fees may also change over time, so it is advisable to check the latest tuition fee standards from the official website or relevant departments of the school before applying.

Furthermore, there are other fees to consider, such as registration fees, examination fees, material fees, etc. These fees will also vary depending on the school and major. When registering for self-taught undergraduate studies, it is important to carefully read official documents and regulations to ensure that you understand all the fees to be paid and the payment methods.

In conclusion, the tuition fees for self-taught undergraduate studies have some variations, and the specific amount needs to be determined based on the school and courses. If you are concerned about tuition fees, the best approach is to directly contact the main examination institution you have chosen and inquire about their latest tuition fee standards and related charges.